Mathematics for IGCSE & O level - Circle Theorems (Section 2 - No. 16)
What relationship exists between the angles marked with letters in the circles?
Angles in the same segment are always equal.
The angle between a tangent and a chord is equal to the angle in the alternate segment.
Opposite angles of a cyclic quadrilateral are supplementary.
The angle at the centre is half the angle at the circumference.
Giải thích
First three options are correct, and the angle at the center is twice, not half, the angle at the circumference.