Carcass wrote:

The figure above represents a semicircular archway over a flat street. The semicircle has a center at O and a radius of 6 feet. What is the height h, in feet, of the archway 2 feet from its center? 
A. √2 
B. 2 
C. 3 
D. 4√2 
E. 6
Let's add the radius of 
6 feet to the diagram to get: 

From here, we can see the 
right triangle hiding within the diagram, which means we can apply the Pythagorean Theorem. 
Se can write: h² + 2² = 6²
Simplify: h² + 4 = 36
So, we get: h² = 32
This means h = √32 
Check the answer choices. . . √32  is not among them. 
Looks like we need to simplify √32 
We'll use the fact that √(xy) = (√x)(√y) 
So, √32 = √[(16)(2)]  = (√16)(√2)  = (4)(√2) = 4√2
Check the answer choices. . . D
Answer: D
Cheers, 
Brent