Question 66

If the curved surface area of a right circular cone is 10010 sq cm and its slant height is 91 cm, ﬁnd its total surface area.

Solution

Let radius of cone = $$r$$ cm and slant height = 91 cm

Curved surface area of cone = $$\pi r l = 10010$$

=> $$\frac{22}{7} \times r \times 91 = 10010$$

=> $$22 \times 13 \times r = 10010$$

=> $$r = \frac{10010}{22 \times 13} = 35$$

$$\therefore$$ Total surface area of cone = $$\pi r(l + r)$$

= $$(\frac{22}{7} \times 35) (91 + 35)$$

= $$22 \times 5 \times 126 = 13860 cm^2$$

=> Ans - (D)

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