Geometry & TrigonometryHard
Circles
Work with arc length, sector area, central angles, inscribed angles, and the equation of a circle.
Sample SAT Problem
A circle has equation (x − 2)² + (y + 3)² = 25. What is its radius?
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Step-by-Step Solution
Radius = √25 = 5. Center is at (2, −3).
Key Tips from Pamela
- Standard form: (x − h)² + (y − k)² = r². Center is (h, k), radius is r.
- Arc length = (central angle / 360°) × 2πr.
- An inscribed angle is half the central angle that subtends the same arc.
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