A conical tent made of canvas has a base that is 20 feet across and a slant height of 14 feet. To the nearest whole unit, what is the area of the canvas, including the floor? Use 3.14 for p.

Question

e.mccormick · Answer

So use the formula for surface area of a cone, or if in calculus use the method of shells.  
The base (floor) is $\pi r^2$
The cone (canvas) is $\pi r s$
Where r = radius = half the diamiter (across) and s = slant height.