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Circle Theorems Worksheet — GCSE — Advanced

Circle Theorems worksheet for Key Stage 4 / GCSE (Ages 14-16). Advanced level maths practice, aligned to the UK National Curriculum. Print-ready with answer key included.

MathsKey Stage 4 / GCSE (Ages 14-16)Circle Theoremsadvanced
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Advanced Circle Theorems

Key Stage 4 / GCSE (Ages 14-16) - Advanced Level

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Instructions: This worksheet explores advanced circle theorems. Each activity requires critical thinking and problem-solving skills. Use the diagrams and hints provided to solve the problems.

1

Identifying Circle Theorems

Examine the diagram of the circle. Identify and name the circle theorems that apply to the angles and segments shown. Write your answers in the spaces provided.

1. Angle ABC is subtended by arc AC. Name the theorem:

2. Line segment AD is a tangent at point A. Name the theorem relating angle BAD and angle ACD:

3. Diameter EF creates a right angle at point G on the circumference. Name the theorem:

2

Calculating Angles Using Circle Theorems

Use your knowledge of circle theorems to calculate the missing angles in the diagram. Show your working clearly.

1. Given angle ACB = 40°, calculate angle ADB:

2. If angle PQR = 70° and PR is a diameter, find angle PSR:

3. In a cyclic quadrilateral ABCD, angle ABC = 85° and angle CDA = 95°. Find angle DAB:

3

Circle Theorems and Proofs

Provide a proof for each of the following statements using circle theorems. Write your proof in clear, logical steps.

1. Prove that the angle subtended by an arc at the centre is twice the angle subtended at the circumference.

2. Prove that opposite angles of a cyclic quadrilateral sum to 180°.

4

Real-world Application of Circle Theorems

Read the scenario below and apply circle theorems to solve the problem. Provide a detailed explanation of your solution.

A circular park has a path that forms a chord of the circle. The path is 60 metres long and subtends an angle of 90° at the centre of the park. Calculate the radius of the park.

5

Comparing Circle Theorems

Compare the following pairs of circle theorems. Describe how they are similar and how they differ. Use examples to illustrate your points.

1. The angle in a semicircle theorem vs. the tangent-segment theorem.

2. The alternate segment theorem vs. the cyclic quadrilateral theorem.

6

Circle Theorems in Geometry Problems

Solve the following geometry problems using circle theorems. Show all your working clearly.

1. In a circle, the radius is 10 cm. A chord is 16 cm long. Find the distance from the centre of the circle to the chord.

2. Two tangents are drawn from a point outside the circle to points A and B on the circle. If angle AOB = 120°, find the angle between the tangents.

7

Exploring Tangents and Secants

Investigate the properties of tangents and secants in circles. Answer the questions based on the diagram provided.

1. If a tangent and a secant are drawn from a point outside the circle, explain the relationship between the segments formed.

2. Calculate the length of the tangent segment if the secant segment is 15 cm and the external segment is 9 cm.

8

Circle Theorems and Coordinate Geometry

Use coordinate geometry to verify circle theorems. Show your calculations and reasoning.

1. Prove that a triangle inscribed in a circle with one side as the diameter is a right triangle using coordinate geometry.

2. Verify the theorem that states the perpendicular from the centre of a circle to a chord bisects the chord using coordinates.

Answer Key

Activity 1: Angle at the centre ; Alternate segment theorem ; Angle in a semicircle

Activity 2: 80° ; 20° ; 95°

Activity 3: Proofs vary

Activity 4: Radius is 42.43 metres

Activity 5: Comparisons vary

Activity 6: 8 cm ; 60°

Activity 7: The tangent segment is 12 cm

Activity 8: Proofs vary

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