Question 7

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Jambmaths question: 

The sum of interior angles of a regular polygon is 1800o. Calculate the size of one exterior angle of the polygon

Option A: 

12o

Option B: 

18o

Option C: 

30o

Option D: 

24o

Jamb Maths Solution: 

$\begin{align}  & \text{Sum of interior angle or a regular polygon is given as }(n-2){{180}^{\circ }} \\ & (n-2){{180}^{o}}={{1800}^{o}} \\ & n-2=10,\text{ }n=12 \\ & \text{Each interior angle will be }\frac{1800}{12}={{150}^{o}} \\\end{align}$Using the diagram aboveThe exterior angle will be 1800 – 1500 =30o Alternatively,The sum of the exterior polygon is 360oSince the polygon has 12 sides12 × θ  =360o$\theta =\frac{{{360}^{o}}}{12}={{30}^{o}}$

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