GMAT Preparation Math Review Geometry Circle Solutions Part 2
1.
If we draw red lines we will have the right triangle with a side of r, 5-r and 5+r. We can apply Pythagorean Theorem.
52 + (5-r) 2 = (5+r) 2
r=1.25
Correct choice is B
2.
If we draw red lines we will have the right triangle with a side of 2, 2 and 2+r. We can apply Pythagorean Theorem.
22 + 2 2 = (2+r) 2
r=2√2 - 2
Correct choice is C
3.
If we draw red lines we will have the right triangle with a side of 4 and 4.
A(Shaded) = 2 *( A(1/4 of Circle Sector)-A(Triangle in red))
= 2(1/4 π 42 – (1/2) 4 4 )
= 8π – 16
Correct Choice is D
4.
If we draw red lines we will have the right triangle with a side of 4 and 4.
A (Shaded) = 2(A(square) - A(1/4 of Circle Sector)) = 2(4*4 - (1/4 * π * 42))
= 32-8π
Correct choice is B