JAMB - Mathematics (2005 - No. 20)
The sum of the interior angle of a regular polygon is 1800o. Calculate the size of one exterior angle of the polygon
30o
24o
18o
12o
Forklaring
Sum of interior ∠s = 1800o
∴(n - 2) 180o = 1800o
180n -360o = 1800o
180n = 1800o + 360o
180n = 2160o
n = 2160o/180o
n = 12 sides
Each exterior ∠ = 360o/n
= 360o/12
= 30o
∴(n - 2) 180o = 1800o
180n -360o = 1800o
180n = 1800o + 360o
180n = 2160o
n = 2160o/180o
n = 12 sides
Each exterior ∠ = 360o/n
= 360o/12
= 30o