Circle theoroms

Angles in the same segment are equal (they are all the same size)

A chord will always sphjlit a circle into 2 segments. There is one at the top and bottom

A chord with a dot in the middle is the diameter, which splits circle into 2 semi circles.Angles in a semi circle are 90 degrees

The angle at the centre is twice the angle at the circumference. You can also say it in reverse. The angle at the circumference is half the angle at the centre.

If all 4 points of a quadrilateral is touching the circumference, its called a cyclic quadrilateral.

Opposite angles in a cyclic quadrilateral add to 180 degrees.

A tangent meets a radius at 90 degrees.

Tangents from the same point are equal in length

If we draw a line from the centre of the circle to the angle at the point of the tangent, it bisects the angle. (splits it in half). Since both the tangents from a point are equal and both are 15 degrees, in total the angle is 30 degrees

When a tangent makes an angle with a chord, it is equal to the angle the tangent makes with the circumference