CBSE > Class 09 > Mathematics | CBSE Board | Homework Help

Let {tex}\triangle{/tex}ABC be an equilateral triangle.
We know that in an equilateral triangle the altitude is same as the median.
So, BD=DC=a cm
By Pythagoras theorem,
AC²=AD²+DC²
{tex}\Rightarrow{/tex} AD²=AC²-DC²
{tex}\Rightarrow{/tex} AD²=(2a)² -a²
{tex}\Rightarrow{/tex} AD²= 4a² - a²
{tex}\Rightarrow{/tex} AD²=3a²
{tex}\Rightarrow{/tex} AD={tex}\sqrt 3 {/tex} a cm
So, length of the altitude is {tex}\sqrt 3 {/tex} a cm.

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If the area of an equlateral triangle is 81underroot 3

Posted by Kashish Kashish 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Firoj Khan 6 years, 3 months ago

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How to prove the angle sum property of a triangle??

Posted by Samiksha Joshi 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Mr Mady 6 years, 3 months ago

Take a line parallel to the base . Angle 1 on top angle 2 on either right or left and third one on the third space.The sides (other than base) form transversal on two parallel lines. 1+4+5=180° on the line parallel to base 2=4 and 3=5 both alternate interior angles .So 1+4+5=180° then 1+2+3=180°(proved)

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Firoj Khan 6 years, 3 months ago

A+b+c=180

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Find a rational number between -2 and 4

Posted by Mohd Asif 6 years, 3 months ago

CBSE > Class 09 > Mathematics

5 answers

Ramavath Karanusha 6 years, 3 months ago

-1, 0,1,2,3

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Ankit Kumar 6 years, 3 months ago

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Firoj Khan 6 years, 3 months ago

2 3 4

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Shashank Gupta 6 years, 3 months ago

2 3 4

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Shreya Raj 6 years, 3 months ago

2,3

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Find a rational number between 1/9 and 2/9

Posted by Mohd Asif 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Gaurav Seth 6 years, 3 months ago

Let us take 4 rational number between 1/9 and 2/9
So, 4+1=5

1/9 and 2/9
1/9x5/5=5/45
2/9x5/5=10/45

Hence, The rational number between 1/9 and 2/9 are
6/45,7/45,8/45,9/45

Rational number between

Are

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Mohd Asif 6 years, 3 months ago

Find a rational number between 1/9 and 2/9

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X=9-4√5 X^-1/x^

Posted by Jitesh Prajapati 6 years, 3 months ago

CBSE > Class 09 > Mathematics

0 answers

ANSWER

Simplify 81x¹² - 256y¹²

Posted by Naveendeep G N 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Shreya Raj 6 years, 3 months ago

(9x^6 )^2 -(16y^6)^2 (9x^6+16y^6)(9x^6-16y^6) (9x^6+16y^6)[(3x^3)^2-(4y^3)^2] (9x^6+16y^6)(3x^3+4y^3)(3x^3-4y^3)

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103³

Posted by Shameema Salam11 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Mr Mady 6 years, 3 months ago

(100+3)^3 = 100^3+3^3+3(100^2)(3)+3(100)(3^2) = 1000000+27+90000+27001 = 1092727

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No One 6 years, 3 months ago

103×103×103

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What is (a+b)²

Posted by Anshit Tardeja 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Naveendeep G N 6 years, 3 months ago

a² + b²+2ab

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Manoj Das 6 years, 3 months ago

a2+b2+2ab

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Show that sum of all sides of a quadrilateral is greatet than the sum of its diagonals

Posted by Sree Kala 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Sia ? 6 years, 3 months ago

Given: A quadrilateral ABCD
To prove: The sum of all the sides is greater than the sum of its diagonals.
i.e. AB + BC + CD + DA > AC + BD
Construction: Join AC and BD.
Proof: Since sum of any two sides of a triangle is greater than the third side.
Therefore,
In {tex}\triangle{/tex}ABC
AB + BC > AC ...(i)
In {tex}\triangle{/tex}ACD
AD + DC > AC ...(ii)
In {tex}\triangle{/tex}ABD
AB + AD > BD ...(iii)
and in {tex}\triangle{/tex}BCD
BC + CD > BD ...(iv)
adding (i), (ii), (iii) and (iv) we get
2AD + 2DC + 2AB + 2BC > 2AC + 2BD
{tex}\Rightarrow{/tex} AB + BC + CD + DA > AC + BD
Hence proved.

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Give me a all the formula's of that chapter's. Chapter 12 Heron's formula. Chapter 13 surface areas AND volume's

Posted by Tmndp Sidhu 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Shreya Raj 6 years, 3 months ago

0Thank You

Anjali Arya 6 years, 3 months ago

See in book

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To prove ab||bc given abc perpendicular to bca

Posted by Kavita Bhola 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Kavita Bhola 6 years, 3 months ago

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Shreya Raj 6 years, 3 months ago

question is wrong..?

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4x2

Posted by Daksh Tiwari 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Anjali Arya 6 years, 3 months ago

0Thank You

Pankaj Singh 6 years, 3 months ago

4 x 2 =8

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To verify the identity of ( a -b)=

Posted by Darshika Pandey 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Shreya Raj 6 years, 3 months ago

(a-b)=?

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Expand (3a-5b-c)²

Posted by Shameema Salam11 6 years, 3 months ago

CBSE > Class 09 > Mathematics

3 answers

Arti Singh 6 years, 3 months ago

(3a-5b-c)²= 3a²+5b²+c²+2(3a)(-5b)+2(-5b)(-c)+2(-c)(3a) = 9a²+25b²+c²-30ab+10bc-6ac

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Shreya Raj 6 years, 3 months ago

1Thank You

Pankaj Singh 6 years, 3 months ago

(3a +(-5b)+(-c)² = (3a)² + (-5b)² + (-c)² + 2(3a)(-5b) + 2(-5b)(-c) + 2(3a)(-c) = 9a² + 25b² + c² - 30ab + 10bc - 6ac

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In given fig ab ||cd.find the value of x,y,Z

Posted by Noorain Warsi 6 years, 3 months ago

CBSE > Class 09 > Mathematics

2 answers

Noorain Warsi 6 years, 3 months ago

I don,t know how to drawnin mobile

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Anjali Arya 6 years, 3 months ago

Where is figure.

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Construct a triangle ABC in which BC =8cmB=45° and AB-AC=3.5cm

Posted by Thyagraj Javali 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Anjali Arya 6 years, 3 months ago

Construction is Not possible in mobile.

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8(3a -2b )square - 10 ( 3a -2b )

Posted by Shashi Raj 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Shristi Arya?? 6 years, 3 months ago

8(3a-2b)² - 10(3a-2b)= 546a + 236b -80ab

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To obtain mirror images of figures with respect to a given line on a graph paper

Posted by Muskan Agrawal 6 years, 3 months ago

CBSE > Class 09 > Mathematics

0 answers

ANSWER

To verify infinite number of solution by plotting graph of ax+by+c=0

Posted by Muskan Agrawal 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Kuldeep Singh 6 years, 3 months ago

A=0,B=0

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2/2+2

Posted by Amresh Yadav 6 years, 3 months ago

CBSE > Class 09 > Mathematics

3 answers

Mr Mady 6 years, 3 months ago

0Thank You

Anjali Arya 6 years, 3 months ago

1/2

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Muskan Agrawal 6 years, 3 months ago

2/2+2 2/2+2/1 2+4/2 6/2 3

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Images with respect to the today population as per India census 2011 are given below population in thousands 12 530 20158 villages 2015 32 35 36 7 find the average population in each village

Posted by Anand Kolly 6 years, 3 months ago

CBSE > Class 09 > Mathematics

0 answers

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Postulate

Posted by Sonia Dhillon 6 years, 3 months ago

CBSE > Class 09 > Mathematics

1 answers

Satyabrat Sahu 6 years, 3 months ago

Postulates need to proof but if this question come in exam write the theorem because postulate is correct answer but in CBSE it is wrong. If you want to know about postulate, see in last page of 5 chapter of math book of ncert

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Find the angle whose comlement is itself

Posted by Balaraju Goud 6 years, 3 months ago

CBSE > Class 09 > Mathematics