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P2-1

Circle Properties

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PAPER 2 TOPIC 1

Circle Properties

P2-1.1 Angles in a Circle

Theorem 1: Angle at Centre = 2 × Angle at Circumference

For the same arc, central angle = 2 × inscribed angle

Theorem 2: Angles in Same Segment are Equal

All inscribed angles subtended by the same arc are equal

Theorem 3: Angle in Semicircle = 90°

Angle inscribed in a semicircle is always a right angle

P2-1.2 Cyclic Quadrilateral

Theorem 4: Opposite Angles are Supplementary

$\angle A + \angle C = 180°$, $\angle B + \angle D = 180°$

P2-1.3 Tangent Properties

Theorem 5: Tangent ⊥ Radius

Tangent is perpendicular to radius at point of tangency

Theorem 6: Tangents from External Point are Equal

From external point P, two tangents PA = PB

📘 MathsKiller Textbook Series | P2-1 Circle Properties

© 2025 MathsKiller