Question

What is the area of a regular dodecagon (12 sides) with side length of 9 cm and apothem of 16.8 cm?

Answer 1

For this case we have that the area of a regular polygon is given by:

$A = \frac {P * a} {2}$

Where:

P: It is the perimeter

a: It is the apothem

Since we have a dodecagon, then the perimeter is:

$P = 9 * 12\\P = 108 \ cm ^ 2$

Then, the area is:

$A = \frac {108 * 16.8} {2}\\A = 907.2 \ cm ^ 2$

ANswer:

Option B