Question

the base of an isosceles triangle is 4 cm and it's perimeter is 20 cm. Find the area of the triangle​

Answer 1

Answer:

A =4 √14 sq.cm

Step-by-step explanation:

Let the sides of the triangle are  a, a  and b.

Given      

b = 4cm    

Perimeter = 20

a + a + b = 20

2a + 4 = 20

2a = 20 - 4

2a = 16

a = 16/2 = 8                    

∴  c also 8

S = perimeter / 2 =  20 / 2 = 10cm

A = √ S . ( S - a ) . ( S - b ) . ( S - c )

A = √ 10 . ( 10 - 8 ) . ( 10 - 4 ) . ( 10 - 8 )

A = √ 10 . ( 2 ) . ( 6 ) . ( 2 )

A = √240

A = √2x2  x2x2 x3x5

A =4 √3x5

A =4 √14 sq.cm