Mensuration

Cuboid

Cuboid, cube, cylinder, cone, sphere, and hemisphere each have fixed formulae for surface area and volume. For example, a cuboid has lateral surface a

When a cone is cut parallel

When a cone is cut parallel to its base, two figures are obtained: a cone and a frustum. A frustum is not a cone itself. The shape of a glass used to

A sector is the part enclosed

A sector is the part enclosed by two radii and the arc joining their end points. A minor sector uses the minor arc, and a major sector uses the major

The area of a sector

The area of a sector is A = θ/360 × πr2, where θ is the central angle and r is the radius. Since the central angle of a circle is 360°, the sector are

The length of an arc

The length of an arc is l = θ/360 × 2πr. The arc length is the same fraction of the circumference as the central angle is of 360°. The ratio of arc le