Question 68

If the curved surface area of a right circular cone is 3080 sq cm and its slant height is 35 cm, ﬁnd its total surface area?

Solution

Let radius of the cone = $$r$$ cm and slant height, $$l = 35$$ cm

Curved surface area of cone = $$\pi r l = 3080$$

=> $$\frac{22}{7} \times r \times 35 = 3080$$

=> $$22 \times 5 \times r = 3080$$

=> $$r = \frac{3080}{110} = 28$$

$$\therefore$$ Total surface area of cone = $$\pi r l + \pi r^2$$

= $$3080 + \frac{22}{7} \times (28)^2$$

= $$3080 + 2464 = 5544 cm^2$$

=> Ans - (C)

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