Solve Precalculus Problem: Perimeter & Area of a Pentagon

[pasatom20]

HI guys, I'm really confusing about this Q., and I hope you guys can give me some help.

- Find the perimeter and the area of a regular pentagon inscribed in circle of radius 9.

 

[Euclid]

Break the inscribed pentagon into something simpler, such as triangles.

 

[HallsofIvy]

Draw lines from the center of the circle to the vertices of the pentagon. What is the angle between these lines?

 

[pasatom20]

I just figured out how to work on the problem. thanks everyone for helping me.