arc 9 videos

Arc Length
Geometry Circles
How to define arc length and how it is different from arc measure; how to calculate the length of an arc.
arc length arc measure concentric circles fraction circumference radius diameter 
Central Angles and Intercepted Arcs
Geometry Circles
How to define a central angle and find the measure of its intercepted arc; how to describe the intercepted arcs of congruent chords.
chord central angle intercepted arc arc measure congruent chords side side side shortcut 
Angles in Semicircles and Chords to Tangents
Geometry Circles
How to prove that an angle inscribed in a semicircle is a right angle; how to solve for arcs and angles formed by a chord drawn to a point of tangency.
inscribed angle semicircle tangent chord intercepted arc 
Inscribed Angles
Geometry Circles
How to calculate the measure of an inscribed angle.
inscribed angle intercepted arc central angle congruent arcs 
Secants
Geometry Circles
How to define a secant; how to find the length of various secants in circles.
secant intercepted arcs proportion arc measure tangent chord 
Parts of a Circle
Geometry Geometry Building Blocks
How to define a circle and identify its main parts.
center chord diameter radius congruent circles concentric circles arc minor arc major arc semicircle central angle 
Area of a Sector
Geometry Area
How to derive the formula to calculate the area of a sector in a circle.
sector central angle intercepted arc circle radius area 
Similar Triangles in Circles and Right Triangles
Geometry Similarity
How to determine if two triangles in a circle are similar and how to prove that three similar triangles exist in a right triangle with an altitude.
similar inscribed angles intercepted arc right angle circle 
Cyclic Quadrilaterals and Parallel Lines in Circles
Geometry Circles
How to prove that opposite angles in a cyclic quadrilateral are congruent; how to prove that parallel lines create congruent arcs in a circle.
inscribed angles cyclic quadrilaterals parallel lines alternate interior angles