Question

Two angles of a polygon are right angles and every other angle is 120degree . find the number of sides of the polygon

Answer 1

sum of the exterior angle other than 90 
                                                       = 180 
therefore no. of side = 180/60
                                 =3 
                                 =3 +2
                                 = 5

Answer 2

Answer:

5 sides.

Step-by-step explanation

Let the number of sides be n,

Then sum of angles =

2*90+(n-2)*120°

A.T.Q

(n-2)*180°=2*90+(n-2)*120°. 180n - 360° = 180° + 120n - 240

⇒ 180n - 120n = 180 - 240 + 360

⇒ 60n = -60 + 360

⇒ 60n = 300

⇒ n = 300/60

or, n = 5