Pls help, some question I already have the answer but its different from the book answer

You need to calculate the height of the cone which would be OV, not VB

Using Pythagorean theorem:

OV = sqrt(37^2-12^2)

OV = 35

Now you have the height to solve everything.

This is a semi circle so volume and surface area would be 1/2 of a full cone.

A) v = 1/2 x pi x r^2 x h/3

V = 1/2 x pi x 12^2 x 35/3

V = 1/2 x pi x 144 x 35/3

V = 840pi

B) sa =1/2 x pi x r(r + sqrt(h^2+r^2))

Sa = 1/2 x pi x 12(12+ sqrt(35^2+12^2))

Sa= 923.63 round as needed.

C) volume of hemisphere with 4cm diameter:

2/3 x pi x 2^3 = 5.33pi

Divide volume of semi cone by volume of hemisphere:

840pi/5.33pi = 157.5