Question

The base of an isosceles triangle is 80cm and its area is 360cm square find the perimeter of triangle

Answer 1

Answer:

perimeter of the isoceles triangle is 162cm.

Step-by-step explanation:

We know, in an isoceles triangle two sides are equal.

Let's say each sides measures x cm.

We have given base = 80cm

And area = 360cm.

Area of an isoceles triangle is = ½.b.h

Where,

• b is base
• h is height

Finding height,

By Pythagoras theorem,

=>> (x)² = (40)² + (h)²

=>> x² = 1600 + h²

=>> x² - 1600 = h²

=>> √x² - 1600 = h

Now,

Area of the triangle = ½.b.h

=>> 360 = ½.(80).(√x² - 1600)

=>> 360 = 40(√x² - 1600)

=>> 360/40 = √x² - 1600

=>> 9 = √x² - 1600

Squaring both sides,

=>> (9)² = (√x² - 1600)²

=>> 81 = x² - 1600

=>> 81 + 1600 = x²

=>> 1681 = x²

=>> √1681 = x

=>> 41 = x

We have three side as 80cm, 41cm each equal sides.

Perimeter = 41*2 + 80

= 82 + 80

= 162cm.