Question

The curved surface area of frustum cone is 1,200 cm. The diameter of a cone is 50 and 12 cm. Find the slant height. (Use $\pi$ = 3).

• A. 12.22 cm
• B. 11.22 cm
• C. 14.22 cm
• D. 12.90 cm

Answer 1

The correct option is D 12.90 cm

Curved surface area = $\pi$(R + r)s

Diameter = radius $\times 2$

Radius, R = 25 cm, r = 6 cm

1,200 = $3\times (25+6)\times s$

1,200 = $3\times \left(31\right)\times s$

1,200/93 = s

Slant Height = 12.90 cm