Corbett Maths
Circle Theorems
Circles are ripe with theorems. Viewers of a YouTube video watch as the narrator describes a set of eight theorems on circles. The video shows a diagram for each theorem and provides a brief explanation for each one.
Khan Academy
Khan Academy: Geometry: Inscribed and Central Angles
Proof that the measure of an inscribed angle is half the measure of a central angle when the angles intercept the same arc. [14:16]
Imagine Learning Classroom
Learn Zillion: Lesson Video: 'Show Angle Relationships in Cyclic Quadrilaterals'
In this lesson, you will show angle relationships in cyclic quadrilaterals by using the Central Angle Theorem. [3:27]
Khan Academy
Khan Academy: Perpendicular Bisectors: Area Circumradius Formula Proof
Proof of the formula relating the area of a triangle to its circumradius.
Khan Academy
Khan Academy: Inscribed Angles
Sal finds a missing inscribed angle using the inscribed angle theorem.
Khan Academy
Khan Academy: Inscribed Shapes: Find Inscribed Angle
Using either the inscribed angle theorem or the fact that two inscribed angles that intercept the same arc must be congruent.
Khan Academy
Khan Academy: Inscribed Angle Theorem Proof
Proving that an inscribed angle is half of a central angle that subtends the same arc.