The sum of the interior angle of a regular poly... - JAMB Mathematics 2005 Question

Sum of interior ∠s = 1800^o

∴(n - 2) 180^o = 1800^o

180n -360^o = 1800^o

180n = 1800^o + 360^o

180n = 2160^o

n = 2160^o/180^o

n = 12 sides

Each exterior ∠ = 360^o/n

= 360^o/12

= 30^o