JAMB - Mathematics (2021 - No. 19)
Each of the interior angles of a regular polygon is 140°. How many sides has the polygon?
9
8
7
5
説明
Each interior angle = \(\frac{(n - 2)180}{n}\)
140 = \(\frac{(n - 2)180}{n}\)
Cross multiply:
140n = 180n - 360
40n = 360
n = 9 sides ( A Nonagon)