Advertisement Remove all ads

Two Angles of a Polygon Are Right Angles and the Remaining Are 120° Each. Find the Number of Sides in It. - Mathematics

Sum

Two angles of a polygon are right angles and the remaining are 120° each. Find the number of sides in it.

Advertisement Remove all ads

Solution

Let the number of sides = n

Sum of interior angles = (n - 2) × 180°

= 180n - 360°

Sum of 2 right angles = 2 × 90° = 180°

∴ Sum of other angles = 180n - 360° - 180°

= 180n - 540°

No.of vertices at which these angles are formed = n - 2

∴ Each interior angle = `(180"n" - 540)/("n" - 2)`

∴ `(180 "n" - 540)/("n" - 2) = 120°`

180n - 540 = 120n - 240

180n - 120n = - 240 + 540

60n = 300

n = `300/60`

n = 5

Concept: Sum of Angles of a Polynomial
  Is there an error in this question or solution?
Advertisement Remove all ads

APPEARS IN

Selina Concise Mathematics Class 8 ICSE
Chapter 16 Understanding Shapes
Exercise 16 (A) | Q 11 | Page 181
Advertisement Remove all ads
Advertisement Remove all ads
Share
Notifications

View all notifications


      Forgot password?
View in app×