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Which of the following is not true for an exterior angle of a regular polygon with n sides?
(a) Each exterior angle = 360°/n
(b) Exterior angle = 180° - interior angle
(c) n = 360°/exterior angle
(d) Each exterior angle = (n - 2) × 180°/n

Solution:

We have to find the option that is not true for an exterior angle of a regular polygon with n sides.

An exterior angle is defined as the angle that is formed outside the polygon between a side of the polygon and its adjacent extended side.

To find the measure of each exterior angle when the number of sides are given,

Exterior angle = 360°/n

On rewriting, we get

n = 360°/exterior angle

To find the measure of each exterior angle when the measure of interior angle is given,

Exterior angle = 180° - interior angle

The sum of interior angles of any polygon (convex or concave) having n sides is(n -2) x 180°.

Therefore, option d is not true.

✦ Try This: Which of the following is true for interior angle of a regular polygon with n sides?

(a) Each exterior angle = 360°/n

(b) Exterior angle = 180° - interior angle

(c) n = 360°/exterior angle

(d) Each exterior angle = (n - 2) × 180°/n

☛ Also Check: NCERT Solutions for Class 8 Maths

NCERT Exemplar Class 8 Maths Chapter 5 Problem 43

Summary:

Each exterior angle = (n - 2) × 180°/n is not true for an exterior angle of a regular polygon with n sides.

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