Question

.
11. The perimeter of an isosceles triangle is 42 cm and its base is 1 times
2
each of the equal sides. Find (i) the length of each side of the triangle,
(ii) the area of the triangle, and (til) the height of the triangle,

plz tell me the ans of the ques..
for class 9 chap heorens formula​

Answer 1

Answer:

hope it will help you

Step-by-step explanation:

Let the equal side of the isosceles triangle be x.

Base of isosceles triangle is

2

3

x.

Given perimeter of isosceles triangle =42 cm and we know that perimeter is sum of all sides, therefore,

x+x+

2

3

x=42

⇒

2

7

x=42

⇒7x=84

⇒x=12

Thus, the equal sides are 12 cm each and base is 18 cm.

Since we have found all the three sides of triangle, therefore we find the area of triangle by Herons formula:

S=

2

18+12+12

=

2

42

=21 cm

A=

21×(21−18)×(21−12)×(21−12)

=

21×3×9×9

=

5103

=71.435=72

Hence, the area of the triangle is 72 cm

2

(approx).