Question

Which one is/ are correct?

• A. Total surface area of cylinder is $2\pi r^2+2\pi rh$
• B. Total surface area of a sphere is $4\pi r^2$
• C. Total surface area of a cone is $\pi r^2+\pi rl$
• D. Total surface area of a square Pyramid is $s^2+4sl.$

Answer 1

Answer: (A), (B), (C)

The correct options are
A Total surface area of cylinder is $2\pi r^2+2\pi rh$
B Total surface area of a sphere is $4\pi r^2$
C Total surface area of a cone is $\pi r^2+\pi rl$

Total SA of cylinder $=$ area of $2$ bases(circles) $+$ lateral SA.

$=2\pi r^{2}h+2\pi rh$

Total SA of sphere $=4\pi r^2$

Total Surface Area of cone $=$ base area $+$ CSA

$=\pi r^2+\pi rl$

Toatal SA of sqared pyramid $=$ base area(square) $+$ CSA

$s^2+4\times \frac{1}{2}s(l^2-{\left(\frac{s}{2}\right)}^2)$

where, $s$ is side of base, $l$ is slant height of pyamid.

Hence, option D is wrong.