Question

a circular mirror is surrounded by a square metal frame. the radius of the mirror is 5x. the side length of the metal frame is 15x what is he area of the metal frame?

Answer 1

Since the side of the square frame is 15x, the area of the frame in whole would be:

(15x)² = 225x²

Now if we subtract out the circle mirror with a radius of 5x, we get:

225x² - πr²
225x² - π(5x)²
225x² - π25x²

We can factor out a 25x² and get:

25x² (9 - π)