成人快手

Circle theorems - Higher - EduqasAngles in the same segment - Higher

Circles have different angle properties described by different circle theorems. Circle theorems are used in geometric proofs and to calculate angles.

Part of MathsGeometry and measure

Angles in the same segment - Higher

The angles at the by the same are equal.

More simply, angles in the same segment are equal.

Angles \(a = a\)

Circle with identical angles, a, at the circumference

Example

Calculate the angles \(p\) and \(q\).

Circle with angles, 52degrees, 40degrees, p and q at the circumference

Angles in the same segment are equal.

\(p = 52^\circ\)

\(q = 40^\circ\)

Proof

Let the obtuse angle MOQ = \(2x\).

Circle with double angle (2x) at centre

Using the circle theorem, the angle at the centre is twice the angle at the circumference.

Angle MNQ = \(x\) and angle MPQ = \(x\).

Two angles (x) at circumference

Therefore angle MNQ = angle MPQ.