Maths Monster
GR.3.2

Circle theorems - angles in a semi-circle

Prove and use facts about the angle in a semicircle being a right angle

3 hand-picked video lessons for this topic, each checked for relevance and clarity, graded by difficulty and labelled by depth. Press play to watch — nothing loads from YouTube until you do.

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2:32
Grade 6–9 Core 🇬🇧 UK

Angle in a Semi Circle Proof

corbettmaths 206K views

Corbett's tight proof of exactly why the angle in a semicircle is always 90 degrees.

13:53
Grade 5–9 Core 🇬🇧 UK

Circle Theorems - GCSE Higher Maths

1st Class Maths 1.8M views

Slick, high-reach GCSE run-through of every circle theorem, with a clear semicircle section.

19:47
Grade 5–9 Core 🇬🇧 UK

Circle Theorems

Maths Genie 324K views

Maths Genie's full GCSE circle-theorems tutorial covering the semicircle rule in depth.