Question

The isosceles triangle has perimeter 40cm and each of the equal sides is 12cm. The area of triangle is:

Answer 1

two equal sides are = 12

let the third side be = x

then

12 + 12 + x = 40cm

24 + x = 40cm

x = (40-24)cm

x = 16cm

so the sides of triangle are 12cm, 12cm and 16cm

using heron's formula,

area of triangle =

$\sqrt{s \: (s - a) \:(s - b) \: (s - c)}$

where s =

$\frac{a + b + c}{2}$

s =

$\frac{40}{2}$

s = 20

area =

$\sqrt{20 \: (20 - 12 )(20 - 12)(20 - 16} )$

$\sqrt{20 \times 8 \times 8 \times 4}$

$8 \times 2 \sqrt{20}$

$16 \sqrt{20}$