Question

PLEASE!!!someone check my answers and explain if I got wrong!!!

A cone is placed inside a cylinder as shown. The radius of the cone is half the radius of the cylinder. The height of the cone is equal to the radius of the cylinder. What is the volume of the cone in terms of the radius, r?

I'm going with v=1/6(pi)r^2 because it's half of 1/3

but im always 2nd guessing myself my other choices are
v=1/12(pi)r^3
v=2(pi)r^3

image below

2nd question

What is the ratio of the radius of a circle to its circumference.

my answer 1/2pi

any ideas????

Answer 1

What is the volume of a cone in terms of height and radius?

Answer 2

In this case the radius is r/2 and the height is r. We just plug those into the formula.

Answer 3

v=1/6r^2 is correct??

Answer 4

First give me the volume of a cone in terms of height and radius.

Answer 5

You can use Google, but I want to make sure we have this general formula correct first.

Answer 6

v=1/3(pi)r^2h

Answer 7

Okay. Now we have to replace r with r/2, and h with r.

Answer 8

What happens when you make this substitution?

Answer 9

v = 1/3(pi)(r/2)^2(r)

Answer 10

You have to simplify.

Answer 11

r^3

Answer 12

r^3/12

Answer 13

Where did pi go?

Answer 14

Anyway, do you understand the answer now?

Answer 15

yes thanks
@wio is the ratio of the radius of a circle to its circumference 1/2pi