From a solid cylinder of height h cm and base radius r cm, a conical cavity of the same height and same radius is drilled out.

If the slant height of the conical cavity is l cm, the surface area of the remaining solid is :

1. 2πrh + πrl

2. 2πrh - πr² + πrl

3. 2πrh + πrl + πr²

4. 2πrh - πrl + πr²

Given,

Radius of cylinder = r cm

Height of cylinder = h cm

Radius of cone = r cm

Height of cone = h cm

Surface area of remaining solid = Total surface area of cylinder - Base area of cone + Curved surface area of cone

= (2πrh + 2πr²) - (πr²) + πrl

= 2πrh + 2πr² - πr² + πrl

= 2πrh + πr² + πrl

Hence, Option 3 is the correct option.