triangle angle sum 161 videos

The Angle Between Vectors
Precalculus Vectors and Parametric Equations
How to compute the angle between two vectors.
dot product angle between vectors position vectors 
Angles: Types and Labeling
Geometry Geometry Building Blocks
How to label an angle and how to differentiate between acute, right, obtuse, and straight angles.
angle acute right obtuse straight vertex side 
Geometric Series
Algebra 2 Sequences and Series
How to find the sum of a geometric series.
geometric series sum of a geometric sequence rate infinite sum finite sum 
Geometric Series
Precalculus Sequences and Series
How to find the sum of a geometric series.
geometric series sum of a geometric sequence rate infinite sum finite sum 
Arithmetic Series
Algebra 2 Sequences and Series
How to find the sum of an arithmetic series.
partial sums arithmetic series sum of an arithmetic sequence 
Arithmetic Series
Precalculus Sequences and Series
How to find the sum of an arithmetic series.
partial sums arithmetic series sum of an arithmetic sequence 
306090 Triangles
Geometry Pythagorean Theorem
How to find the legs and hypotenuse in 306090 triangles when given: the short leg, the long leg, or the hypotenuse.
right triangle short leg long leg hypotenuse 
306090 Triangles
Trigonometry Pythagorean Theorem
How to find the legs and hypotenuse in 306090 triangles when given: the short leg, the long leg, or the hypotenuse.
right triangle short leg long leg hypotenuse 
Adjacent Angles
Geometry Reasoning, Diagonals, Angles and Parallel Lines
How to define adjacent angles.
vertex side coplanar 
The HalfAngle Identities
Trigonometry Advanced Trigonometry
How to use the power reduction formulas to derive the halfangle formulas.
the power reduction formulas the half angle formulas quadrants 
The HalfAngle Identities
Precalculus Advanced Trigonometry
How to use the power reduction formulas to derive the halfangle formulas.
the power reduction formulas the half angle formulas quadrants 
Similar Triangles
PreAlgebra Introductory Geometry
Overview of similarity: congruent angles, proportional corresponding sides

Vertical Angles
Geometry Reasoning, Diagonals, Angles and Parallel Lines
How to define and identify vertical angles.
vertex intersecting lines congruent 
Constructing a Triangle Midsegment
Geometry Constructions
How to define a midsegment in a triangle.
midpoint segment median 
454590 Triangles
Geometry Pythagorean Theorem
How to find the length of a leg or hypotenuse in a 454590 triangle using the Pythagorean Theorem.
isosceles right triangle leg hypotenuse Pythagorean theorem square root 
454590 Triangles
Trigonometry Pythagorean Theorem
How to find the length of a leg or hypotenuse in a 454590 triangle using the Pythagorean Theorem.
isosceles right triangle leg hypotenuse Pythagorean theorem square root 
Applied Linear Equations: Geometry Problem
Algebra 2 Linear Equations
How to find the angles of a triangle by creating a linear equation.
word problem angle measure 
Applied Linear Equations: Geometry Problem
Precalculus Linear Equations and Inequalities
How to find the angles of a triangle by creating a linear equation.
word problem angle measure 
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 
Angle Bisectors and Opposite Side Ratios
Geometry Similarity
How to relate the sides of an angle bisected and the lengths of the opposite side.
angle bisector opposite side ratio proportion