Khan Academy on a Stick
Circles

Language and Notation of the Circle
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Formal definition of a circle. Tangent and secant lines. Diameters and radii. major and minor arcs

Circles: Radius, Diameter and Circumference
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Understanding the relationship between the radius diameter and circumference of a circle.
 Length of an arc that subtends a central angle
 Finding central angle measure given arc length

Parts of a Circle
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Parts of a Circle

Area of a Circle
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Area of a Circle
 Area of a sector given a central angle

Inscribed and Central Angles
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Showing that an inscribed angle is half of a central angle that subtends the same arc

Perpendicular Radius Bisects Chord
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Simple proof using RSH postulate to show that a radius perpendicular to a chord bisects it

Right Triangles Inscribed in Circles (Proof)
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Proof showing that a triangle inscribed in a circle having a diameter as one side is a right triangle

Area of Inscribed Equilateral Triangle (some basic trig used)
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Problem that requires us to figure out the area of an equilateral triangle inscribed in a circle (A little trigonometry used)