What is the area of canvas required to make a conical surface tent with height $35~\text{m}$ and radius of base $84~\text{m}$? 
A conical circus tent is to be made of canvas. The height of the tent is $35~\text{m}$ and the radius of the base is $84~\text{m}$. What is the area of canvas required?

I calculated slant height which came out to be $76.3$ and then I applied lateral surface area of cone formula which is $\frac{22}7\times76.3\times84$
 But my answer is wrong. Right answer is $24024$.
This a gmat exam question.

The slant height is $a=\sqrt{h^2+r^2}=91m$
$$S=\pi  r a \approx 3.14\cdot 84 \cdot 91\approx 24024m^2$$
