Question

Find the area of a regular decagon with radius 4 cm

Answer 1

`A = (5)/(2)t^(2) \sqrt{5 + 2 √(5) }`


`A = (5)/(2) (4)^(2) √(5 + 2(2.236067978)) }`


`A = (5)/(2) (16) √(5 + 4.472135956)`


`A = 40 √(9.472135956)`


`A = 40(3.077683537)`


`A = 123.1073415cm^(2)`

Answer 2

The area is 123.1073415 cm