Question

math's the devil but help plz

Answer 1

Using the apothem, a, and the perimeter, p, the area, A, of a regular polygon is

$A = \dfrac{pa}{2}$

You need to calculate the area of the octagon and subtract the area of the square.
The perimeter is 8 times the side.

$A = \dfrac{pa}{2} - s^2$

$A = \dfrac{8 \times 13 \times 15.69}{2} - 13^2$

$A = 815.88 - 169$

$A = 646.88$