Mathematics
The interior angles of a pentagon are in the ratio 4 : 5 : 6 : 7 : 5. Find each angle of the pentagon.
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Answer
According to the properties of polygons, if a polygon has n sides, then the sum of its interior angles is (2n - 4) x 90°.
A pentagon have 5 sides.
So, sum of its interior angles is:
(2 x 5 - 4) x 90°
= (10 - 4) x 90°
= 6 x 90°
= 540°
It is given that the interior angles of the pentagon are in the ratio 4 : 5 : 6 : 7 : 5. Let each angle be a.
So,
4a + 5a + 6a + 7a + 5a = 540°
⇒ 27a = 540°
⇒ a =
⇒ a = 20°
The angles are:
4a = 4 x 20° = 80°
5a = 5 x 20° = 100°
6a = 6 x 20° = 120°
7a = 7 x 20° = 140°
5a = 5 x 20° = 100°
Hence, the measures of the angles are 80°, 100°, 120°, 140° and 100°.
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