Question

The total surface area of a cone of base radius “r” and slanted height “l” is equal to __________

(a) πrl + 2πr^2

(b) 2πrl + 2πr^2

(c) πrl + πr^2

(d) 2πr^2

This question was addressed to me during an internship interview.

This key question is from Surface Area of a Right Circular Cone in portion Surface Areas and Volumes of Mathematics – Class 9

Answer 1

Right option is (c) πrl + πr^2

The explanation is: Total surface area of a cone of base radius “r” and slanted height “l”

= Curved surface area of a cone + Base area of a cone

= πrl + πr^2.