obtuse triangles 50 videos

Similarity Shortcuts
Geometry Similarity
How to determine if two triangles are similar using a shortcut.
similar triangles AA SAS SSS proportion congruence 
CPCTC
Geometry Triangles
How to use the principle that corresponding parts of congruent triangles are congruent, or CPCTC.
corresponding parts or congruent triangles proofs 
Using a Protractor
Geometry Geometry Building Blocks
How to use a protractor to measure an angle.
protractor angle acute obtuse right 
Inverse Trigonometric Functions
Geometry Basic Trigonometry
How to use inverse trig functions to find angles in right triangles.
trigonometry right triangle inverse sine cosine tangent 
SSS and SAS
Geometry Triangles
How to use the SAS and SSS shortcuts to determine the congruence of two triangles.
triangle congruence side side side side angle side 
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 
Trigonometric Ratios: Sine
Geometry Basic Trigonometry
How to define the sine ratio and identify the sine of an angle in a right triangle.
trigonometry ratio right triangle sine SOH CAH TOA 
Trigonometric Ratios: Cosine
Geometry Basic Trigonometry
How to define the cosine ratio and identify the cosine of an angle in a right triangle.
trigonometry ratio right triangle sine SOH CAH TOA 
Trigonometric Ratios: Tangent
Geometry Basic Trigonometry
How to define the tangent ratio and identify the tangent of an angle in a right triangle.
trigonometry ratio right triangle sine SOH CAH TOA 
Using the Pythagorean Theorem to find a Missing Hypotenuse
Geometry Pythagorean Theorem
How to calculate the hypotenuse in a right triangle given the lengths of the legs using the Pythagorean Theorem.
Pythagorean theorem leg hypotenuse right triangle 
Pythagorean Theorem Proofs
Geometry Pythagorean Theorem
How to prove the Pythagorean Theorem using Algebra to show the area of the smaller square plus the area of four triangles is equal to the area of the larger square.
right triangle area of a square binomial squared area of a triangle side leg hypotenuse 
Constructing a Median
Geometry Constructions
How to define a median in a triangle.
midpoint vertex segment median 
Constructing the Orthocenter
Geometry Constructions
How to construct the orthocenter of a triangle.
point of concurrency orthocenter altitude construction 
Center and Apothem of Regular Polygons
Geometry Area
How to define the apothem and center of a polygon; how to divide a regular polygon into congruent triangles.
center circumscribed circle inscribed polygon isosceles triangle regular hexagon 
Why SSA and AAA Don't Work as Congruence Shortcuts
Geometry Triangles
How to determine which congruence shortcuts do not work and why.
congruent triangles shortcuts 
The Law of Sines
Geometry Basic Trigonometry
How to define the law of sines.
law of sines ratios triangles 
The Law of Cosines
Geometry Basic Trigonometry
How to define and use the law of cosines.
law of cosines ratios triangles 
Polygon Angle Sum
Geometry Polygons
How to derive the formula to find the sum of angles in any polygon.
triangle angle sum diagonal polygon 
Equiangular Polygon Sums
Geometry Polygons
How to find the measure of one angle in any equiangular or regular polygon.
equiangular regular congruent triangles sum 
Solving Formulas
Geometry Area
How to strategize about solving formulas for variables; how to solve the area of a rectangle formula for base and height; how to solve the area of a triangle formula for base and for height.
formulas isolating a variable rectangle area triangle area trapezoid area regular polygon area