geometry//alg 2 help please?

Question

im not sure on all of them so please correct me if i am wrong

http://smg.photobucket.com/albums/v700/XoXCoNnIeEe/?action=view¤t=037-1.jpg
http://smg.photobucket.com/albums/v700/XoXCoNnIeEe/?action=view¤t=036-1.jpg

Answer 1

1.) You forgot to square the right side of the equation:
√(x^2 + 5) = x + 3
x^2 + 5 = x^2 + 6x + 9
-4 = 6x
x = -4/6 = -2/3
Whenever you square both sides you have to check your answers because extraneous answers can be introduced:
√[(-2/3)^2 + 5] = -2/3 + 3
√[(4/9) + 5] = 7/3
√49/9 = 7/3

2.) OK

3.) OK

4a.) You are asked for the ratio of the perimeter of the square to the circumference of the circle. You have the numbers reversed. Order is important:
24 : 18.85

4b.) OK

4c.) √(5^2 + 9^2 + 12^2) = 15.81

4d.) VB = 2VA
π(4^2)(hA) = 2π(6^2)(hB)
hA/hB = 2(36)/16 = 9/2
hA : hB = 9 : 2