A conical tent is $8$ $m$ high and the radius of its base is $6$ $m$. A conical tent is $8$ $m$ high and the radius of its base is $6$ m. Find
(i) Slant height of the tent
(ii) Cost of the canvas required to make the tent, if the cost of $1$ $m^2$ canvas is $\$70$.
What I've tried so far,
Height=$8$ $m$
Radius=$6$ $m$
Slant height=$\sqrt{r^2 + h^2}
=10$ $m$

Lets start by deriving the Surface area of a cone ignoring the base

Let the height be $h$
We can see by Pythagoras that the slant height $s = \sqrt{h^2+r^2}$ 
The shape of the material would, when flattened out look like this

Which we can see could be cut from a circle of radius $s$
We know the formula for the area of a circle and we know what proportion of the circle we need
Surface Area $A = \pi \cdot s^2 \cdot \dfrac{2 \cdot \pi \cdot r}{2 \cdot \pi \cdot s} = \pi \cdot s \cdot r$
I'll leave it as an exercise to enter from here all you need to do is multiply the area by the cost of the canvas to finish.
