the half angle formulas 64 videos

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 
Same Side Interior and Same Side Exterior Angles
Geometry Reasoning, Diagonals, Angles and Parallel Lines
How to describe same side interior and same side exterior angles and their special properties.
parallel lines angles congruence interior exterior transversal 
Equation of a Circle
Geometry Pythagorean Theorem
How to derive the equation for a circle using the distance formula.
distance formula radius center circle 
Distance Formula
Geometry Pythagorean Theorem
How to derive the equation for the distance between two points using the Pythagorean Theorem.
distance coordinate plane ordered pair segment 
Using a Protractor
Geometry Geometry Building Blocks
How to use a protractor to measure an angle.
protractor angle acute obtuse right 
Area of a Segment
Geometry Area
How to derive the area of a segment formula.
segment sector triangle area radius central angle shaded area 
Area of Kites and Rhombuses
Geometry Area
How to derive the area formula of a kite based on the rectangle formula; how to calculate the area of a rectangle using diagonal lengths.
kite area diagonals consecutive sides vertex angle non vertex angle bisect perpendicular rhombus 
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 
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 
Special Isosceles Triangle Properties
Geometry Triangles
How to identify a segment from the vertex angle in an isosceles triangle to the opposite side.
isosceles triangle angle bisector altitude median 
Corresponding Parts of Similar Triangles
Geometry Similarity
How to relate corresponding altitudes, medians and angle bisectors in similar triangles.
similar triangles altitude median angle bisector proportional 
ASA and AAS
Geometry Triangles
How to use the ASA and AAS shortcuts to determine the congruence of two triangles.
triangle congruence angle side angle angle angle side 
Radii to Tangents
Geometry Circles
How to define a tangent line; how to determine the angle a radius to a tangent forms.
tangent radius right angle point outside the circle perpendicular 
Isosceles Triangles
Geometry Triangles
How to define isosceles triangles, their components and how to determine their properties.
vertex angle leg base base angle converse remote interior angles 
Area of Triangles
Geometry Area
How to derive the area of a triangle formula using the rectangle area formula.
area triangles rectangles altitude 
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 
Parallelogram Properties
Geometry Polygons
How to identify all of the special properties of parallelograms and use them to solve problems.
opposite sides parallel opposite angles same side interior angles diagonals bisect consecutive angles rhombus rectangle square 
Constructing the Incenter
Geometry Constructions
How to construct the incenter using a compass and straightedge.
point of concurrency angle bisectors equidistant 
Area of Regular Polygons
Geometry Area
How to derive the formula to calculate the area of a regular polygon.
area apothem side hexagon isosceles triangle perimeter equilateral equiangular