Sector Perimeter

What is Sector Perimeter?

The total distance around the outside of a sector, formed by adding the two bounding radii to the arc between them, so that for an ordinary sector the perimeter is 2r plus r theta. It is a length and is measured in linear units. The expression describes one particular shape rather than stating a universal law: in a compound figure a radius may lie inside the region and be exposed on neither side, or only part of it may lie on the boundary, so the perimeter of any region is found by tracing the edge that is actually exposed.

This definition is part of the Circular Measure chapter in Cambridge O Level Additional Mathematics.

Concepts related to Sector Perimeter

• exposed boundary
• internal construction line
• trace
• do not quote

Common mistakes with Sector Perimeter

• Omitting the two radii from a sector perimeter. Why it fails The arc is one of three boundary pieces, not all of them. It feels like the answer because it is the piece that required a formula. Fix Count the pieces of the outline, then count the terms in your sum. They must match.