Circle Theorem

Circle Theorem

90° angles formed from a cirle

Angles formed on the circumference of a semi-circle from each side of a diameter are equal to 90°.

90° angles formed with a circle.

Angle formed between the radius of a circle and the tangent point are always 90°.

Multiple Choice

Find the measure of the angle marked (y) in the diagram.

• 30

• 60

• 90

• 180

Multiple Choice

The diagram shows a tangent to a circle with centre O. Find the angles marked x and y in each case

• x = 12°

  y = 156°

• x = 100°

  y = 50°

• x = 62°

  y = 28

• x = 30°

  y = 60°

Multiple Choice

In the diagram, TP and TQ are tangents to a circle with centre O. Find each value of x

• 70

• 90

• 110

• 140

Multiple Choice

In the diagram, TP and TQ are tangents to a circle with centre O. Find each value of x

• 38

• 52

• 90

• 72

Multiple Choice

Find the value of the angle marked x in the diagram.

• 45

• 50

• 90

• 100

Multiple Choice

Find the value of the angle marked x in the diagram.

• 43

• 45

• 47

• 53