Instructional Video
Khan Academy

Khan Academy: Inscribed Quadrilaterals Proof

9th - 10th Standards
Sal uses the inscribed angle theorem and some algebra to prove that opposite angles of an inscribed quadrilateral are supplementary.
Instructional Video
Khan Academy

Khan Academy: Proof: Perpendicular Radius Bisects Chord

9th - 10th Standards
Simple proof using RSH postulate to show that a radius perpendicular to a chord bisects it
Instructional Video
Khan Academy

Khan Academy: Inscribed Shapes: Find Diameter

9th - 10th Standards
Find the diameter of a circle using an inscribed right triangle.
Instructional Video
Khan Academy

Khan Academy: Solving Inscribed Quadrilaterals

9th - 10th Standards
Example showing supplementary opposite angles in inscribed quadrilateral.
Instructional Video
Khan Academy

Khan Academy: Geometric Constructions: Circle Inscribed Equilateral Triangle

9th - 10th Standards
Sal constructs an equilateral triangle that is inscribed inside a given circle using compass and straightedge.
Instructional Video
Khan Academy

Khan Academy: Proof: Radius Is Perpendicular to a Chord It Bisects

9th - 10th Standards
Sal proves that if a radius in a circle is drawn so it bisects a chord, then the radius is also perpendicular to that chord. The proof uses SSS congruence.