Calculate arc length and sector area using the central angle.
A sector is a 'pizza slice' of a circle. Arc length (part of the circumference): [formula] Sector area (part of the circle's area): [formula] Where theta is the central angle in degrees. In radians: Arc = rtheta, Sector area = frac{1}{2}r^2theta
Example: A circle with radius 12 cm has a sector with central angle 60°. Find the arc length and sector area.
Think of the fraction frac{theta}{360°} as 'what fraction of the whole circle is this sector?' Then multiply by the full circumference or area.
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