Each of the interior angles of a regular polygon is 140o. Calculate the sum of all the interior angles of the polygon
-
A.
1080o -
B.
1260o -
C.
1800o -
D.
2160o
Correct Answer: Option B
Explanation
Each interior angle = 140
(frac{(n – 2) times 180}{n} = 140)
(n – 2) x 180 = 140n
150 – 360 = 140n
180m – 140n = 360
40n – 360
n = (frac{360}{40})
n = 9
Sum of all interior angles = (n – 2) x 180
= (9 – 2) x 180
= 7 x 180
= 1260