Perimeter of a sector
The perimeter of a sector is the total boundary length of the sector, including the two radii and the curved arc.
Practice This ConceptMain explanation
Teacher explanation
A sector has three boundary parts: one curved arc and two straight radii. So its perimeter is not only the arc length. Students must add the arc length and the two radii together to get the full boundary.
Example
For a sector with radius 6 cm and arc length 5π cm, perimeter = 5π + 12 cm.
Simple analogy
Perimeter of sector = arc plus two spokes.
Common confusion
Students often write only the arc length and forget to add the two radii.
Exam tip
Whenever the word perimeter appears, think total boundary, not just the curved part.
Answer writing and exam use
1-mark use
Write the exact meaning of perimeter of a sector in one clean line.
2-mark use
Define perimeter of a sector and add one example or condition.
3-mark use
Explain perimeter of a sector, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
Open the concept quiz intro first, review the test details, and then start a focused MCQ set from this concept only. Instant score and answer review are live now.
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