Find the area of the regular 20-gon with radius 11 mm.

Question

I need Geometry help!!!

Answer 1

there is a formula that you can use to find the area of a regular polygon given the radius

A=(1/2)(r^2)(sin[360/n])(n) where r=radius and n=number of sides

(other formulas exist if you are given the apothem or one of the sides)

A=(1/2)(11^2)(sin[360/20])(20)

A=(1/2)(121)(sin[18°])(20)

A=(1/2)(121)(0.30901699)(20)

now multiply all the numbers together in whichever order you like

A=(60.5)(0.30901699)(20)

A=(18.6955279)(20)

A=373.9105579 mm^2 (round as you like)