triangle angle sum 161 videos

The Definitions of Sine and Cosine
Precalculus Trigonometric Functions
How we define sine and cosine for all angle measures using the unit circle.
sine cosine right triangle definitions of sine and cosine angles in standard position unit circle definitions of sine and cosine 
Series and Summation Notation
Algebra 2 Sequences and Series
How to define a series.
series sum of a sequence 
Series and Summation Notation
Precalculus Sequences and Series
How to define a series.
series sum of a sequence 
Constructing Altitudes
Geometry Constructions
How to define an altitude and draw them on acute, right, and obtuse triangles.
altitudes perpendicular segment vertex opposite side obtuse acute right triangles 
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 
Using the Pythagorean Theorem to find a Missing Hypotenuse
Trigonometry 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 
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 
Area of a Segment
Geometry Area
How to derive the area of a segment formula.
segment sector triangle area radius central angle shaded area 
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 
Pythagorean Theorem Proofs
Trigonometry 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 
The Law of Sines
Trigonometry Basic Trigonometry
How to define the law of sines.
law of sines ratios triangles 
The Law of Cosines
Trigonometry Basic Trigonometry
How to define and use the law of cosines.
law of cosines ratios triangles 
The Law of Sines
Precalculus Basic Trigonometry
How to define the law of sines.
law of sines ratios triangles 
The Law of Cosines
Precalculus Basic Trigonometry
How to define and use the law of cosines.
law of cosines ratios triangles