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Chapter - 24

CONE AND SPHERE – VOLUME AND SURFACE AREA.

RIGHT CIRCULAR CONE

Right circular cone is a solid formed by the revolution of a right angled triangle about one of the sides containing a right angle.

Fig. – 1

Formula.

1. Volume = (1/3) pr²h, where r = radius of the circular base, h = height of the cone.
2. Curved Surface Area = πrl, where l = slant height and l² = r² + h².
3. Total Surface Area = πr² + πrl = πr(r + l).

FRUSTUM

When the upper portion of the cone is cut off by a plane surface parallel to the base, the remaining solid is called frustum of the cone.

Fig. – 2