Question

The circumference of lower and upper bases of the frustum cone is 13 and 27 mm. The slant height is 34 mm. What is the curved surface area ?

• A. 675 $m{m}^2$
• B. 680 $m{m}^2$
• C. 645 $m{m}^2$
• D. 650 $m{m}^2$

Answer 1

The correct option is B 680 $m{m}^2$

Curved surface area of the frustum cone

= $\frac{1}{2}(2\pi R+2\pi r)l$

= $\frac{1}{2}(13+27)\times 34$

= $40\times 17$

= 680 $m{m}^2$