Surface Areas and Volumes Class 9 Notes Maths - Chapter 13

Chapter: 13

What Are Surface Areas And Volumes ?

Cone

Whose radius = r, height = h, Slant height = l

• Short lenght (l) = √(r2 + h2)
CONE

• Curved surface area = πrl

• Volume = (1/3)πr2h

• Total surface area = πr(l + r)

Sphere

SPHERE

Whose radius = r

• Surface Area = 4πr2
• Volume =(4/3)πr3

Hemisphere

HEMISPHERE

Whose radius = r

• Curved surface area = 2πr2
• Total surface area = 3πr2
• Volume =(2/3)πr3

Points To Remember

• Cube has all the edges of same length.

• In cuboid one of the dimension (length, bredth or height) is different.

• In cube & cuboid, area of four faces (except top & bottom) is taken as lateral surface area.

• In cube & cuboid, area of all four faces, top & bottom is taken as total surface area.

• Area of the rectangle sheet is taken as the lateral surface of the cylinder.

POINTS TO REMEMBER

• A solid generated by the revolution of right triangular surface about any one leg is called right circular cone.

• The height of the hemisphere is same as the radius of the hemisphere.