Geometry :(?

Question

1) Find the total surface area of a cylinder with radius 3 and height 8.

2) A sphere has area 64 pi. What is it's volume?

3) What is the volume of a cube with edge 2?

4) A rectangular solid with length 8 and width 3 has volume 28. Find it's height.

I have the answers but I just need it to be explained. Thanks!

Answer 1

1) As = 2B+Al = 2pi 3^2 + 2pi(3)(8), where As is the total surface area, B is the base area, and Al is the lateral area.

2) 64pi = 4pi r^2 => r = 4 => v = (4/3)pi(4^3)

3) v = 2^3 = 8

4) h(3)(8) = 28 => h = 28/24 = 7/6

Answer 2

1) surface area of cylinder = (2 * pi * r) * (r + h)
2) volume of sphere = (4/3) * pi * r^3
3) volume of cube = s^2
4) volume of rectangular solid = l * w * h
r = radius, h = height , s = side, l = length, w = width

Answer 3

SA of a cylinder = 2 pi r^2 + 2 pi r h
V of sphere = 4/3 pi r^3
V of a cube = edge^3
V of a rectangular solid : V= lwh so h = v divided by (lw)

Answer 4

1) 2*pi *3^2 + 2*pi*3*8 = 18pi+48pi = 64pi

2) 4pir^2 = 64
2rsqrt(pi) = 8
r = 4/sqrt(pi)
v=4/3 pi r^3 = 4/3 pi 64/(pisqrt(pi)) =256/(3sqrt(pi))

3) V= s^3 = 2^3 = 8

4) h = 28/(8*3)= 28/24 = 7/6

Answer 5

As = 2B+Al = 2pi 3^2 + 2pi(3)(8)
So, the answer given before me is correct.

Answer 6

Geometry...Yuck! :(

Happy?


geometry isn't real algebra! Not even close, stick to algebra!

Answer 7

well if you have your answer, then explain how you solved it