The sum of the interior angles, s, in an n-sided polygon can be determined using the formula s=180(n−2), where n is the number of sides. Using this formula, how many sides does a polygon have if the sum of the interior angles is 1,260°? Round to the nearest whole number. 6 sides
7 sides
8 sides
9 sides

(D.)

The polygon has 9 sides

Step-by-step explanation:  

We need to equate the given expression to the given value and solve for n.

The sum of the interior angles, s, in an n-sided polygon is given by the expression:

We want to use this formula, to calculate how many sides has a polygon if the sum of the interior angles is 1,260°.

We solve the following equation for n.

Divide through by 180 to get:

Add 2 to both sides to get:

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12