WAEC - Mathematics (2010 - No. 21)
The sum of the exterior of an n-sided convex polygon is half the sum of its interior angle. find n
6
8
9
12
Explanation
sum of exterior angles = 360o
Sum of interior angle = (n - 2) x 180
360 = \(\frac{1}{2}\) x(n - 2) x 180(90o)
360 = \(\frac{1}{2}\) x(n - 2) x 90o
\(\frac{360}{90}\) = a - 2
4 = n - 2
n = 4 + 2 = 6
Sum of interior angle = (n - 2) x 180
360 = \(\frac{1}{2}\) x(n - 2) x 180(90o)
360 = \(\frac{1}{2}\) x(n - 2) x 90o
\(\frac{360}{90}\) = a - 2
4 = n - 2
n = 4 + 2 = 6
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