Question

How do I do these problems?

Answer 1

Problems

Answer 2

Do you know the formula for the volume of a cone?

Answer 3

yeah

Answer 4

Remember that the oblique cone has the same formula as the straight cone.

Answer 5

i know but i dont know how to do the pi thing

Answer 6

the base is 4 right?

Answer 7

I will do it for the first case. In the first case,
h=4 ft
R=4/2=2 ft
Then
\[V=\frac{\pi r^2 h}{3}=\frac{\pi 2^2\cdot2}{3}=\frac{8}{3}\pi=2.67\pi\ ft^3\approx 3 \ ft^3\]

Answer 8

why 2? as base

Answer 9

Sorry, I forgot the pi in the last step.
\[3\pi \ ft^3\]

Answer 10

Well, the formula I have used is this,
\[V=\frac{\pi r^2 h}{3}\] In the problem you have a circular base whose radius is the half of the diameter. They give you the diameter, 4. So your radius is r=4/2=2. Ok?

Answer 11

i thought the formula for volume of a cone is 1/3 x b x h

Answer 12

Exactly, but in the "b" it is not the "base" it is the "area of the base", ok?

Answer 13

In this case, the b, I mean, the area of the base is,
\[b=\pi r^2\]

Answer 14

oh so whenever a formula asks for base it the are so i would find the area formula for the shape right?

Answer 15

base=area?

Answer 16

In this formula, yes. But remember, the area of the base.

Answer 17

okay

Answer 18

Do the same for the other problems, and you will obtain the answer easily.

Answer 19

i did it alreay

Answer 20

Except in the last one, where they give you the radius and not the diameter. In that case put r= 2 m, directly.

Answer 21

Ok, perfect.

Answer 22

thank you

Answer 23

You're welcome.