Differentiation of Geomertic Objects

[URGENT] Differentiation of Geomertic Objects

1. Homework Statement

A sector of a circle has area 100cm². Show that the perimeter of this sector is given by te formula P = 2r + 200/r

2. Homework Equations

Area of sector = (angle/360) x pi x r^2
Permiter of sector = (angle/360) x 2 pi x r

3. The Attempt at a Solution

I've tried but i don't really have time to write it all out. Can someone just show me how to do this one, so that i can try the other questions in the chapter

Thanks