Inscribed Angle Theorem | Explained Visually

Why is the angle at the centre twice the angle at the circumference when both angles stand on the same arc? Discover the reason through a visual proof using equal radii, isosceles triangles and one diameter. We build the proof step by step, cover the addition and subtraction cases, and explain why a major intercepted arc requires a reflex central angle. Then work through an example and try a practice question yourself. Pause the video if you want a longer time to think before watching the solution. You’ll learn how to: • Identify the arc that does not contain the circumference vertex. • Match the central angle to that same arc. • Use the inscribed angle theorem in both directions. • Avoid confusing a reflex central angle with the smaller angle. If you found this video useful, like this video and subscribe for more visual maths lessons. #CircleTheorems #Geometry #InscribedAngleTheorem Chapters 0:00 One arc, two viewpoints 0:21 Choose the correct intercepted arc 1:00 Equal radii and isosceles triangles 1:35 Proving the basic case with a diameter 2:14 Proof by adding angles 2:52 Proof by subtracting angles 3:32 Major arcs and reflex central angles 4:14 Worked example: centre to circumference 4:53 Your turn: practice question 5:35 Practice solution 6:10 Summary of steps 6:45 More visual maths lessons