Hi,
I need to use this formula(below) to find the answers of these 4 questions. I found the answers but I need help to use the formula below:
Find the measure of one base angle.
central angle = 360/9 = 40
2 * side angle + central angle = 180
2 * side angle + 40 = 180
2 * side angle = 140
side angle = 70°

Use a trig ratio to find the height of one triangle.
tan(70°) = h/(8/2)
h = 4*tan(70°)
h = 10.99 in

Use A = 1/2 bh to find the area of one triangle.
A = 1/2 (8)(10.99)
A = 43.96 in2

Find the area of the entire polygon.
A = 43.96*9
A = 395.64 in2
The Questions:
1. An equilateral triangle with a side of 1 inch
3. A regular pentagon with a side of 3 centimeters
4. A regular hexagon with a side of 10 cm
5. A regular heptagon with a side of 7 inches.