If the sum of the measures of the interior angles of a polygon is 1980°, how many sides does it have

Hello from MrBillDoesMath!

n = 13

Discussion:

Generally for a polygon with "n" sides, the sum of the interior angles is given by (n-2)* 180. We need to solve

(n-2) * 180 = 1980                =>  divide both sides by 180

(n-2)          = 1980/180         => as 1980/180 =11

n-2 = 11                                 => add 2 to both sides

n = 11 + 2 = 13

Hence the polygon has 13 sides ( and is called a "triskaidecagon"!)

Thank you,

MrB

correct answer:

b.(19,-2)

none of these

step-by-step explanation:

23 + 34 add up to 57 so just inform the teacher of this really stupid mistake