### Theory:

Right circular cylinder:
A cylinder whose bases are circular shape and the axis joining the two centres of the bases perpendicular to the planes of the two bases is called a right circular cylinder.
Properties of right circular cylinder:

1. The right circular cylinder have one rectangle and two circles.

2. The line joining the centres of the two base circles is called the axis of the right circular cylinder.

3. The diameter of two circles are parallel to each other.
Curved surface area of a right circular cylinder:
C. S. A. $$=$$ Circumference of a circle $$\times$$ length of the cylinder

$$=$$ $$2 \pi r \times h$$    $$[$$Since $$\text{length} = \text{height}]$$

$$=$$ $$2 \pi r h$$

Curved surface area of a right circular cylinder $$=$$ $$2 \pi r h$$ sq. units.
Total surface area of a right circular cylinder:
T. S. A. $$=$$ Curved surface area $$+$$ Area of $$2$$ circles

$$=$$ $$2 \pi r h$$ $$+$$ $$2 \times \pi r^2$$

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

$$=$$ $$2 \pi r (r + h)$$

Total surface area of a right circular cylinder $$=$$ $$2 \pi r (r + h)$$ sq. units.
Oblique cylinder:

This is also a cylinder but not right circular cylinder. The axis joining the two centres of the bases is not perpendicular to the planes of the two bases. It is called as an oblique cylinder.