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Find the area of a triangle …

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Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42 cm

Posted by Zayn Malik 3 years, 7 months ago

CBSE > Class 09 > Mathematics

5 answers

Arhaan Mallik 3 years, 7 months ago

S=42/2=21

Commando 3 years, 7 months ago

40/2

Anshu Agrawal 3 years, 7 months ago

let, side a=18 cm, side b=10cm, and c =x and the perimeter is 42 cm now , to find the c , 18+10+x=42 28+x=42 x=42-28 x=14cm. so, c=14cm S=a+b+c/2 S=18+10+12/2 S=20cm Area of triangle by herons formula=√ S(S-a)(S-b)(S-c) =√ 20(20-18)(20-10)(20-12) =√20 X 2 X 10 X 8 =√5 X 4 X 2 X 5 X 2 X 4 X 2 =5 X 4 X 2 √ 2 =40√2 cm² . This is your answer

Akanksha Kumari 3 years, 7 months ago

Given Side a = 18 cm Side b = 10 cm Perimeter = 42 cm = a + b + c Putting value 42 = 18 + 10 + c 42 = 23 + c 42 - 28 = c Now S = ( a + b + c)/2 Putting value S = 42 / 2 S = 21 Now according to heron's formula Area of triangle √{s(s-a)(s-b)(s-c)} Putting value √{21(21-18)(21-10)(21-14)} √{21(3)(11)(7)} √4851 21√11 cm Square Áñßwér

Pravin S 3 years, 7 months ago

let, side a=18 cm, side b=10cm, and c =x and the perimeter is 42 cm now , to find the c , 18+10+x=42 28+x=42 x=42-28 x=14cm. so, c=14cm S=a+b+c/2 S=18+10+12/2 S=20cm Area of triangle by herons formula=√ S(S-a)(S-b)(S-c) =√ 20(20-18)(20-10)(20-12) =√20 X 2 X 10 X 8 =√5 X 4 X 2 X 5 X 2 X 4 X 2 =5 X 4 X 2 √ 2 =40√2 cm² .

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