Question

Assertion (A): Curved surface area of a right circular cone is
$\pi \times$ radius of base $\times$ slant height.

Reason (R): Total surface area of a right circular cylinder is
$\pi \times (radiusofbase{)}^2$ + $\pi \times$ radius of base $\times$ slant height.

Which of the following is correct?

• A. Both A and R are true and R is the correct explanation of A.
• B. Both A and R are true and R is not the correct explanation of A.
• C. A is true and R is false.
• D. A is false and R is true.

Answer 1

The correct option is C A is true and R is false.

We know that,
Total surface area of cone
$=\pi rl+\pi r^2$
Curved surface area of cone
$=\pi rl$

Now,
Total surface area of cone
$=$ curved surface area + area of base

So, total surface area of cone depends upon curved surface area.

In the reason, it is mentioned as total surface area of cylinder not that of cone.

Hence, assertion is true and reason is false.