Math Is Fun Forum

Hi,
I need help to use this formula in these questions.
Formula:
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

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.
Please help me ASAP!!