Question

The surface area of the frustum cone is given its base radius, R = 12 cm and top radius, r = 10 cm. The height of the cone is 12 cm. Find the slant height of the cone.

• A. $2\sqrt{37}$ cm
• B. $2\sqrt{5}$ cm
• C. 24 cm
• D. $3\sqrt{5}$ cm

Answer 1

The correct option is A $2\sqrt{37}$ cm

Slant height of a cone = $\sqrt{(R-r{)}^2+h^2}$
= $\sqrt{(12-10{)}^2+{12}^2}$
= $\sqrt{(2{)}^2+144}$
= $\sqrt{148}$
= $2\sqrt{37}$ cm