Question

find the sum of the angle measures of each polygon.21 - gon

Answer 1

To be able to determine the sum of all angles in a 21-gon or a polygon with 21 sides will be using the following formula:

$(n\text{ - 2) x 180}$

Where,

n = number of sides

We get,

$(n\text{ - 2) x 180}$$\text{ (21 - 2) x 180}$$\text{ 19 x 180}$$\text{ 3,420}^{\circ}$

Therefore, the sum of all angles in a 21 - gon is 3,420°.