Question

Calculate the area of an equilateral triangle whose height is 20 cm. Find the area of triangle whose sides are 17 cm 8 cm and 15 cm

Answer 1

Given height of equilateral triangle = 20 cm

Area of equilateral triangle with

height 'h' = $\frac{h^2}{\sqrt{3}}$

$\therefore$ Area of equilateral triangle = $\frac{(20{)}^2}{\sqrt{3}}$

$=\frac{400}{\sqrt{3}}\times \frac{\sqrt{3}}{\sqrt{3}}$

$=\frac{400\sqrt{3}}{3}$ sq. cm

Given sides of triangle

17 cm . 8 cm . 15 cm

By Pythagorous theorem

$(15{)}^2+(8{)}^2=(17{)}^2$

It is a right angled triangle

$\therefore$ Area of triangle = $\frac{1}{2}\times b\times h$

$=\frac{1}{2}\times 15\times 8$

= 60 sq cm