what is the area of the regular pentagon below
688.2 ft
850.7 ft
951.1 ft
1,376.4 ft

Answer:
A
Step-by-step explanation:
By definition, all sides of a regular polygon are equal in length. If you know the length of one of the sides, the area is given by the formula:
[tex]A=\dfrac{s^2\cdot n}{4\tan \frac{180^{\circ}}{n}},[/tex]
where s is the side length, n is the number of sides.
In your case, s=20 ft, n=5,so
[tex]A=\dfrac{20^2\cdot 5}{4\tan \frac{180^{\circ}}{5}}=\dfrac{400\cdot 5}{4\tan 36^{\circ}}=\dfrac{500}{0.73}\approx 688.2\ ft^2 [/tex]
For this case we have that by definition, the polygon area shown is given by:
[tex]A = \frac {p * a} {2}[/tex]
Where:
p: It is the perimeter
a: It is the apothem
So, the perimeter is:
[tex]p = 5 * 20\\p = 100 \ ft[/tex]
On the other hand, the apothem is given by:
[tex]tag (36) = \frac {10} {a}\\a = \frac {10} {tag (36)}\\a = \frac {10} {0.72654253}\\a = 13.7638191669247[/tex]
Finally, the area is:
[tex]A = \frac {100 * 13.7638191669247} {2}\\A = 688.19096[/tex]
Rounding off we have:[tex]688.2 \ ft ^ 2[/tex]
Answer:
Option A