1fully worked

Work out the volume of a cone with radius $3$ cm and height $7$ cm.

1$V=\tfrac13\pi r^2 h$Write $V=\tfrac13\pi r^2 h$

2$V=\tfrac13\pi(3)^2(7)=21\pi$Substitute $r$ and $h$

3$=66.0$ cm$^3$Evaluate to 3 s.f.

Check - Which measurement is squared in the formula?

A the height $h$B the radius $r$C both $r$ and $h$D neither

2you finish it

Work out the volume of a cone with radius $4$ cm and height $9$ cm.

1$V=\tfrac13\pi(4)^2(9)$Write $V=\tfrac13\pi r^2 h$

2$=48\pi$Substitute $r$ and $h$

3Evaluate to 3 s.f.

Check - Why is there a $\tfrac13$ in the formula?

A a cone has one third the volume of the cylinder with the same base and heightB because there are three dimensionsC to make it a fractionD it should be $\tfrac12$

3you finish it

Work out the volume of a cone with radius $5$ cm and height $6$ cm.

1$V=\tfrac13\pi(5)^2(6)$Write $V=\tfrac13\pi r^2 h$

2Substitute $r$ and $h$

3Evaluate to 3 s.f.

Check - What is $\tfrac13\pi(25)(6)$ as a multiple of $\pi$?

A $150\pi$B $50\pi$C $450\pi$D $25\pi$

4you do it all

Work out the volume of a cone with radius $6$ cm and height $10$ cm.

1Write $V=\tfrac13\pi r^2 h$

2Substitute $r$ and $h$

3Evaluate to 3 s.f.

Check - The height given is the perpendicular height. Which height would be WRONG to use here?

A the perpendicular heightB the slant heightC the radiusD the diameter