What are the circle theorems relating to tangents
The angle between a tangent and a chord is equal to the angle in the alternate segment.
Two tangents from the same point are equal in length.
A tangent meets a radius at 90 degrees.
What is the circle theorem relating to triangles
A triangle formed by 2 radii and a chord is an isosceles.
Circle theorem relating to the angle at the centre
The angle at the centre is twice the angle at the circumference.
Circle theorem relating to semi circles
The angle in a semicircle is a right angle
(separated by diameter)
Circle theorem relating to segments
Angles in the same segment are equal
Circle theorem relating to quadrilaterals
Opposite angles in a cyclic quadrilateral add up to 180 degrees.
Circle theorem relating to perpendicular lines
Perpendicular lines from the centre bisect the chord.
