**Surface Areas and Volumes class 9** – If l, w and h are length, width, and height of a cuboid then volume of a cuboid is equal to (l x w x h) cubic units. Similarly, the Surface area of cuboid is equal to 2(lw + wh + lh) sq. units. Also, the length of Diagonal of a cuboid is equal to l2 + w2 + h2 units. Let ‘a’ unit be the length of each edge of a cube. Then, the volume of a cube is equal to a3 cubic units. Similarly, the Surface area of cube is equal to 6a2 sq. units. Also, the length of Diagonal of a cube is equal to 3a units. Let, ‘r’ be the radius of base and ‘h’ be the Height of a cylinder, then, volume of a cylinder is given by (πr2h) cubic units. Similarly, the Curved surface area of a cylinder is given by (2πrh) sq. units. Also, the total surface area of a cylinder is given by 2πr(h + r) sq. units. Let, ‘r’ be the radius of base and ‘h’ be the Height of a cone, then, Slant height (l) of a cone is given by l = h2 + r2 units. Therefore, the volume of a cone is equal to \(\frac{1}{3}\pi r^{2}h\)

### Surface Areas and Volumes class 9 Examples

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