Practice | Hashtable

1. What is the total surface area of a right circular cone of height 14 cm and base radius 7 cm?

A. 344.35 cm²

B. 462 cm²

C. 498.35 cm²

D. None of these

Solution:

\begin{aligned} h = 14 c m, r = 7 c m \\ So, l = \sqrt{{(7)}^{2} + {(14)}^{2}} = \sqrt{245} = 7 \sqrt{5} c m \\ ∴ Total surface area \\ = π r l + π r^{2} \\ = (\frac{22}{7} \times 7 \times 7 \sqrt{5} + \frac{22}{7} \times 7 \times 7) c m^{2} \\ = [154 (\sqrt{5} + 1)] c m^{2} \\ = (154 \times 3.236) c m^{2} \\ = 498.35 c m^{2} \end{aligned}

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