<span>3(a+(6x)y) was clearly multiplied out as seen by the 3a and 18xy, so the distributive property was used there. In addition, the commutative and associative properties state that you can rearrange sums, so those were used too </span><span />
A semicircle is half of a circle. The perimeter of the semicircle would be half of the perimeter (circumference) of the entire circle. The formula for circumference is:
C=πd
Using our information, we have
22.92 = 0.5(3.14)d 22.92 = 1.57d
Divide both sides by 1.57:
22.92/1.57 = 1.57d/1.57 14.6≈d
Since the diameter is 14.6, the radius is 14.6/2 = 7.3.