If the radius and height of a right circular cylinder are 21 cm and 5 cm respectively, then the total surface area of the cylinde…

Question

If the radius and height of a right circular cylinder are 21 cm and 5 cm respectively, then the total surface area of the cylinder is (use π=22/7):

1. A. 3432 cm² (Correct answer)
2. B. 5212 cm²
3. C. 3816 cm²
4. D. 4312 cm²

Correct Answer

Option A — 3432 cm²

Detailed Solution & Explanation

The correct answer is 3432 cm².

Key Points

• Total surface area $=2\pi r(r+h)=2\times\dfrac{22}{7}\times21\times(21+5)$.
• $=2\times22\times3\times26=3432$ cm².

Additional Information

• For a right circular cylinder: curved surface area = 2πrh, total surface area = 2πr(r + h) and volume = πr²h.
• The radius 21 is chosen so that 22/7 × 21 cancels to 66 — whenever a radius is a multiple of 7, take π as 22/7 and cancel before multiplying.
• Keep the two surface areas distinct: the total adds the two circular ends, 2πr², to the curved surface.