A n s w e r
Dos of body language:
1. Keep your hands open.
2. Avoid pointing your finger at people.
3.  Tilt your head a bit to show that you are attentive.

Let speed of boat in still water be x km/h and speed of stream be y km/h.

Speed upstream= (x - y) km/h

Speed downstream= (x + y) km/h

On subtracting, we get,

_{On solving, we get,}

Speed of boat in still water = 8 km/h

And, Speed of stream = 3 km/h

The diagonals of a square are equal and bisect each other at right angles.

Detailed proof

Let ABCD be a square. Let the diagonals AC and BD intersect each other at a point O. To prove

that the diagonals of a square are equal and bisect each other at right angles, we have to

prove AC = BD, OA = OC, OB = OD, and ∠AOB = 90º.

In ΔABC and ΔDCB,

AB = DC                   (Sides of a square are equal to each other)

∠ABC = ∠DCB        (All interior angles are of 90)

BC = CB                   (Common side)

So, ΔABC ≅ ΔDCB      (By SAS congruency)

Hence, AC = DB          (By CPCT)

Hence, the diagonals of a square are equal in length.

In ΔAOB and ΔCOD,

∠AOB = ∠COD          (Vertically opposite angles)

∠ABO = ∠CDO          (Alternate interior angles)

AB = CD                     (Sides of a square are always equal)

So, ΔAOB ≅ ΔCOD  (By AAS congruence rule)

Hence, AO = CO and OB = OD     (By CPCT)

Hence, the diagonals of a square bisect each other.

In ΔAOB and ΔCOB,

As we had proved that diagonals bisect each other, therefore,

AO = CO

AB = CB         (Sides of a square are equal)

BO = BO        (Common)

So, ΔAOB ≅ ΔCOB       (By SSS congruency)

Hence, ∠AOB = ∠COB      (By CPCT)

However, ∠AOB + ∠COB = 180⁰        (Linear pair)

2∠AOB = 180⁰

∠AOB = 90⁰

Hence, the diagonals of a square bisect each other at right angles.

Peggy was a rich, pretty American girl. She was intelligent, good at studies and scored good marks. She loved fun and enjoyed teasing Wanda because of her faded blue dress. She kept asking her mockingly how many dresses she had. She took Wanda a dull-headed girl and could never realize how bad Wanda must be feeling about her teasing. She changed her opinion when Wanda won the girl’s medal in the drawing competition. She praised wholeheartedly Wanda’s drawings. She also visited Boggins Heights and wrote letters when Wanda stopped coming to school.

Cash A/c Dr. 1940

Cash discount A/c Dr. 60

Roma's A/c Dr. 2000

To sales A/c 4000

( being goods sold to Roma )

Explanation:

Trade discount = 20% of 5000 = 1000

Trade discount is not recorded in the books of accounts.

Cash discount is only allowed on the amount which is being paid in cash at the time of transition.

Cash discount = 3 % of 2000 = 60

• The Harappans ate a wide range of plant and animal products, including fish and meat, wheat, maize, millets, pulses, rice and another eatables.
• Cattle, sheep, goat, buffalo and pig were domesticated by the Harappans for their sustenance.
• The evidence of wild species like boar, deer and gharial have also been traced from the remains of bones, but it is not sure whether the Harappans hunted these animals themselves or obtained meat from other hunting community.
• Archaeological evidences suggested that oxen were used for ploughing and two different crops were grown together. As most of the sites are located in semi-arid lands, it is evident that water from canals and wells was used for irrigation.

A particular level of hierarchy in the classification of living beings is called as a taxon. A taxon is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. For example, the basic level of classification is species, followed by genus, family, order, class, phylum or division, in ascending order. The highest level of classification is known as a kingdom. So each of these categories can be called as a taxon.

• Fungi and algae switch to the sexual mode of reproduction during adverse conditions to bring variations among the individual.
• Such variations help the individuals to adapt to the changed conditions and survive.
• This ensures the continuity of species and also helps in phenomena like speciation.

Or

Sexual reproduction enables organisms to survive during unfavourable conditions as it leads to variation and variation and variation leads to evolution. Evolution can only be done by the organisms which are able to survive the harsh conditions and the organisms that could not would die and won't reproduce further. The organisms that survived would reproduce, will leave their progeny and as the conditions will become more harsh the adaptive organism would survive and reproduce and this results in the evolution of the species. The reason that sexual reproduction is favoured under such conditions because, sexual reproduction leads to evolution and this evolution results in the continuation of the species.

What led Maria to the path of success and why couldn't her mother accompany her?

A) Her trip to U.S for playing tennis.Her mother couldn't accompany because of visa restrictions
B) Her habits. Her mother was unwell and so she could not accompany her
C) Her interest in music. Her mother did not want to go to USA
D) Her Academics. Her mother was busy

A n s w e r

A) Her trip to U.S for playing tennis.Her mother couldn't accompany because of visa restrictions

Her parents refused to pay for her education because Santosh did not follow the family tradition of getting married early and got herself enrolled in a school in Delhi against their wishes.

sorry 32 m = 3200 cm

32 m = 300 cm

Time period is defined as the time required to complete one oscillation.

Frequency is defined as the number of oscillations per unit time. 

Time = 4 sec. Time Period = (4/40) = 0.1 sec

A n s w e r
Sirius is  the brightest star in the sky after the sun , lying in the constellation Canis
Its name is derived from the Greek word Seirios which means  "glowing" or "scorching

A closed path through which the electric current flows is called an electric circuit. The direction of electric current in an electric circuit is from the positive terminal to the negative terminal. This is opposite to the direction of flow of electrons; which is from the negative terminal to the positive terminal.

There are eight bones that surround your brain: one frontal bone; two parietal bones, two temporal bones, one occipital bone, one sphenoid bone and one ethmoid bone.

eight bones

There are eight bones that surround your brain: one frontal bone; two parietal bones, two temporal bones, one occipital bone, one sphenoid bone and one ethmoid bone. These eight bones make up the cranium. Another 14 bones in the face make up the entire skull.

• Prehistory: Time period in the past when there was no paper or the written word and hence no books or written accounts of events. Information about such an age is obtained from excavations which reveal paintings, pottery, habitat, etc.
• Drawings and paintings were the oldest form of artistic expression practised by humans. Reasons for such drawings: Either to decorate their homes or/and to keep a journal of events in their lives.
• Lower and Middle Palaeolithic Periods have not shown any evidence of artworks so far. The Upper Palaeolithic Age shows a lot of artistic activities.
• Earliest paintings in India are from the Upper Palaeolithic Age.
• The first discovery of rock paintings in the world was made in India by archaeologist Archibald Carlleyle in 1867 – 68 (in Sohagighat, Mirzapur District, Uttar Pradesh).
• Rock paintings have been found in the walls of caves at Madhya Pradesh, Andhra Pradesh, Uttar Pradesh, Bihar and Karnataka, some in the Kumaon Hills of Uttarakhand.
• Paintings at the rock shelters at Lakhudiyar on the banks of the Suyal River (Uttarakhand) –

1. 3 categories of paintings: man, animal and geometric patterns in black, white and red ochre.
2. Humans in stick-like forms, a long-snouted animal, a fox, a multiple-legged lizard, wavy lines, groups of dots and rectangle-filled geometric designs, hand-linked dancing humans.

• Paintings in Kupgallu (Telangana), Piklihal and Tekkalkota (both in Karnataka)

1. Mostly in white and red ochre.
2. Subjects are bulls, sambhars, elephants, sheep, gazelles, goats, horses, stylised humans and tridents.

• Paintings in the Vindhya ranges at Madhya Pradesh extending into Uttar Pradesh –

1. About 500 rock shelters at Bhimbetka in the Vindhya Hills at Madhya Pradesh.
2. Images of hunting, dancing, music, elephant and horse riders, honey collection, animal fighting, decoration of bodies, household scenes, etc.
3. Bhimbetka drawings can be categorised into 7 Periods.
   1. Period I: Upper Palaeolithic
   2. Period II: Mesolithic
   3. Period III: Chalcolithic

• Two major sites of prehistoric rock/cave paintings in India: Bhimbetka Caves and Jogimara Caves (Amarnath, Madhya Pradesh).

A n s w e r : 0

Degree of constant polynomial is always Zero 
As it doesn’t have any variable, because in actual degree of the polynomial is nothing but the highest power of variable x in it.

A job Application consists of two parts- the covering letter (appeal) and the bio-data/CV.

• Cover letter

The format for the covering letter is similar to the format of a Formal letter. It goes on like-

SENDER’s ADDRESS- The sender’s address is usually put on the top left-hand corner.

DATE- The sender’s address is followed by the date just below it. This is the date on which the letter is being written. It is to be written in expanded form.

RECEIVER’s ADDRESS- Whether to write “To” above the address depends on the writer’s preference. Make sure you write the official title/name/position etc of the receiver, as the first line of the address.

SUBJECT- Then we sum up the purpose of writing the letter in one line. This helps the receiver focus on the subject of the letter in one glance. It is important to underline the subject.

SALUTATIONS- This is where you greet the person you are addressing the letter to. Bear in mind that it is a formal letter, so the greeting must be respectful and not too personal. The general greetings used in formal letters are “Sir” or “Madam”.

BODY- This is the main content of the letter. It is either divided into three paragraphs or two paragraphs if the letter is briefer. The tone of the content should be formal. Do not use any flowery language. Another point to keep in mind is that the letter should be concise and to the point. And always be respectful and considerate in your language.

1. PARAGRAPH 1- Begin the body of the letter by mentioning the source (from where you got to know about the job) of information about the job (e.g., newspaper) along with the day, date and advertisement number. Also mention the post you wish to apply for.
2. PARAGRAPH 2- Here, you are supposed to offer your candidature by briefing about your qualifications, achievements, previous experiences and your strengths. In other words, this paragraph should be an answer to the question: ‘How are you the perfect candidate for the job?’.

Keep in mind that it should be to the point and clear. You should not sound boastful.

• PARAGRAPH 3- In this part of the body, you are supposed to make a reference to the photograph (passport-sized), Bio-data or curriculum vitae and other detailed documents that you have enclosed. You can also appeal for a one-on-one interview.

End the body on a promising note, e.g., Looking forward to your positive response.
COMPLIMENTARY CLOSE- At the end of your letter, we write a complimentary closing. The words “Yours Faithfully” or “Yours Sincerely” are used.
SIGNATURE- Here finally you sign your name. And then write your name in block letters beneath the signature. This is how the recipient will know who is sending the letter.
(NOTE- Mention the name given in the question paper. Do not mention your personal details.)

• Bio-data

After signing, you are supposed to mention the heading “ENCLOSURES” which will include the name of the documents and testimonials attached along with the cover letter. They may include the following-

1. Photograph (Passport-sized)
2. Bio-data or CV
3. Copies of certificates
4. Any other

The Biodata or CV  is generally divided into four parts as follows-

1. Personal Details
2. Qualifications
3. Experience
4. References

It goes like-

BIO-DATA (HEADING)

NAME

FATHER’s NAME

DATE OF BIRTH – In expanded form

ADDRESS

AGE

CONTACT NO.

EMAIL ID

NATIONALITY-Indian

MARITAL STATUS

QUALIFICATIONS-

• Qualifications must be written in tabular form with the above mentioned heads.

WORK EXPERIENCE- It should be written from latest to the oldest along with the duration.

ACHIEVEMENTS

LANGUAGES KNOWN

SKILLS

WEAKNESSES

HOBBIES

REFERENCES

DECLARATION

DATE

PLACE

SIGNATURE

We know that, pair of angles are said to be supplementary angles if their sum is equal to 180∘.

Let, x be the supplement angle for 90o.

so, 

90∘ + x = 180∘

     => x = 90∘

SURFACE AREA OF A CUBOID:

Let us consider a cuboid of length = 1 units Breadth = b units and height = h units

Then we have :
(i) Total surface area of the cuboid =2(l * b + b * h + h * l) sq. units
(ii) Lateral surface area of the cuboid = [2 (1 + b)* h] sq. units
(iii) Area of four walls of a room = [2 (1 + b)* h] sq. units. = (Perimeter of the base * height) sq. units
(iv) Surface area of four walls and ceiling of a room = lateral surface area of the room + surface area of ceiling =2(1+b)*h+l*b
(v) Diagonal of the cuboid = √l2 + b2 + h2

SURFACE AREA OF A CUBE :

Consider a cube of edge a unit.
(i) The Total surface area of the cube = 6a2 sq. units
(ii) Lateral surface area of the cube = 4a2 sq. units.
(iii) The diagonal of the cube = √3 a units.

For more click on the given link:

<a href="https://ncerthelp.com/text.php?ques=1585+Notes+For+Volume+and+Surface+Area++Class+9+Formulas+Download+PDF+%0D%0A" ping="/url?sa=t&source=web&rct=j&url=https://ncerthelp.com/text.php%3Fques%3D1585%2BNotes%2BFor%2BVolume%2Band%2BSurface%2BArea%2B%2BClass%2B9%2BFormulas%2BDownload%2BPDF%2B%250D%250A&ved=2ahUKEwis0YCLkbvtAhVIzTgGHep_DekQFjAIegQICxAC" rel="noopener" target="_blank">Volume and Surface Area Class 9 Notes For Class 9 Formulas ...</a>

(a) The shape of the wavefront in case of a light diverging from a point source is spherical. The wavefront emanating from a point source is shown in the given figure.

(b) The shape of the wavefront in case of a light emerging out of a convex lens when a point source is placed at its focus is a parallel grid. This is shown in the given figure.

(c) The portion of the wavefront of light from a distant star intercepted by the Earth is a plane.

Plane Wavefront

• When the small part of a spherical or cylindrical wavefront originates from a distant source like infinity then the wavefront which is obtained is known as plane wavefront.
• For example: -Rays coming from infinity like Sun.