Area of Circle and Sector
The area of a circle is the surface inside its boundary, and the area of a sector is a fractional part of the circle's area.
Practice This ConceptMain explanation
Teacher explanation
Circle area depends on the square of radius. A sector's area depends on the central angle, just as arc length depends on the same fraction of the full circle.
Example
For radius 7 cm, circle area = 22/7 × 7 × 7 = 154 cm². A 90° sector has area 90/360 × 154 = 38.5 cm².
Simple analogy
Area fills the circle, so radius is multiplied twice.
Common confusion
Students use circumference formula when the question asks for the surface inside a circle.
Exam tip
Area uses square units and r²; circumference or arc length uses length units.
Answer writing and exam use
1-mark use
Write the exact meaning of area of circle and sector in one clean line.
2-mark use
Define area of circle and sector and add one example or condition.
3-mark use
Explain area of circle and 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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