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If the interior angles of a pentagon are in the ratio 1 : 3 : 5 : 7 : 11, then the measure of the smallest interior angle is:
Question

If the interior angles of a pentagon are in the ratio 1 : 3 : 5 : 7 : 11, then the measure of the smallest interior angle is:

A.

10°

B.

20°

C.

25°

D.

15°

Correct option is B

Given:

The interior angles of a pentagon are in the ratio 1 : 3 : 5 : 7 : 11.

Concept Used:

The sum of the interior angles of a polygon with n sides is given by the formula (n - 2) ×\times​ 180°.

A pentagon has 5 sides.

Solution:

Calculate the sum of the interior angles of a pentagon:(5 - 2) ×\times​180° = 3 ×\times 180° = 540°​

Let the angles be x, 3x, 5x, 7x, and 11x.

x + 3x + 5x + 7x + 11x = 540°

27x = 540°

x =540°27 \frac{540° }{ 27}​​

x = 20°

The smallest interior angle is x, which is 20°.

Therefore, the measure of the smallest interior angle is 20°.

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