Q12 of 59 Page 195

Sum of measurement of all interior angles of a polygon is 1800°. Let’s write this number of sides of the polygon.

For a polygon with n sides we have a basic formula for the sum of interior angles of a polygon.

Sum of interior angles = 1800°


1800° = (2n – 4) × 90


1800/90 = (2n – 4)


20 = 2n – 4


2n = 20 + 4


2n = 24


n = 12


Therefore the number of sides of this polygon is 12.


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