Question 27

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Jambmaths question: 

What is the size of each interior angle of a 12–sided regular polygon? 

Option A: 

30o

Option B: 

180o

Option C: 

150o

Option D: 

120o

Jamb Maths Solution: 

Method 1

The total exterior angle of a polygon is 360o

Each exterior angle of a duo-decagon (12- sided polygon) =$\frac{{{360}^{\circ }}}{12}={{30}^{\circ }}$

The interior angle = 180o – 30o = 150o (sum of angles on a straight)

 

Method 2

The total angle in a regular polygon is given by (n – 2) 180o

For a 12 sided polygon

The total angle will be (12 – 2)180o =1800o

Each interior angle will be $\frac{{{1800}^{\circ }}}{12}={{150}^{\circ }}$

Answer : Option C

 

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