What is the perimeter of 5 equal sides and the area is 125?
The area of a regular polygon with n sides each sunit long, perimeter p, and apothem a is given by the formulaA = ans/2 or A = ap/2The 5-sided polygon is a regular polygon (5 equal sides), so that its area equalsA = ans/2 (substitute 125 for A, and 5 for n)125 = 5as/2 (multiply by 2 to both sides)250 = 5as (divide by 5s to both sides)50/s = aLook at the right triangle formed by one half of the side s(base), the apothem a (height), and the side s(hypotenuse).The angle opposite to the apothem equals 108⁰/2 = 54⁰ (one half of the interior angle of the pentagon). So we have:tan 54⁰ = a/(s/2) (substitute 50/s for a)tan 54⁰ = (50/s)/(s/2)tan 54⁰ = 50/s x 2/stan 54⁰/1 = 100/s2 (cross multiply)s2tan 54⁰ = 100s2 = 100/tan 54⁰s = √(100/tan 54⁰) (ignore the negative sign)s ≈ 8.5Thus, the side of the given pentagon is about 8.5 units long, and its perimeter is about 42.5 units.