Question

Find the exterior angle of a triangle if it's interior angle is 120° and also draw the diagram

Answer 1

Given :

The interior angle of triangle = 120°

To Find :

The exterior angle of triangle

Solution :

Since for a triangle, number of side = n = 3

Now,

Exterior angle = $\dfrac{360^{\circ}}{n}$

And

Interior angle = 180° -$\dfrac{360^{\circ}}{n}$

i.e Interior angle =  180° - Exterior angle

∴   Exterior angle =  180° - Interior angle

                             =  180° -  120°

                             =  60°

From Figure ,

In Triangle ABC ,

∠C = interior angle = 120°

And Exterior angle = Ф

So,  Ф  = 180° - 120°

           = 60°

Hence, The Exterior angle of Triangle is 60°  . Answer