Torus
A 3D shape made by revolving a small circle (radius r) along a line made by a bigger circle (radius R).
Property:
- It can be made by revolving a small circle (radius r) along a line made by a bigger circle (radius R).
- It is not a polyhedron
- It has no vertices or edges
Surface Area:
Surface Area = 4 × π2 × R × r
Example:
Find the surface area of torus whose r = 3 and R = 7
Solution:
Surface Area = 4 × π2 × R × r
= 4 × π2 × 7 × 3
= 4 × π2 × 21
= 84 × π2
≈ 829
Volume:
Volume= = 2 × π2 × R × r2
Example:
Find the Volume of torus whose, r = 3 and R = 7
Solution:
Volume= 2 × π2 × R × r2
= 2 × π2 × 7 × 32
= 2 × π2 × 7 × 9
= 126 π2
≈ 1244