Question

A hole of radius 6cm is drilled through a right circular cylinder whose base radius and height are 9cm and 12cm respectively. What is the total surface area of the resulting solid?

A. 117πcm ²
B. 315 πcm²
C. 450πcm²
D. 360πсm²​

Answer 1

CSA of cylinder= 2πr(h+r)

=2 π×9 (21)

= 378π cm²

now

CSA of hole= 2πr

12π cm²