• #### The Double-Angle Formulas - Concept

How to use the sine and cosine addition formulas to prove the double-angle formulas.
• #### The Double-Angle Formulas - Concept

How to use the sine and cosine addition formulas to prove the double-angle formulas.
• #### Using the Inverse Trigonometric Functions - Problem 1

How to prove an identity that involves sin^-1(x) and cos^-1(x).
• #### Using the Inverse Trigonometric Functions - Problem 1

How to prove an identity that involves sin^-1(x) and cos^-1(x).
• #### Two Column Proofs - Problem 2

##### Math›Geometry›Triangles
How to use a two column proof to show that two angles are congruent in a parallelogram with one diagonal.
• #### Pythagorean Theorem Proofs - Concept

##### Math›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.
• #### Pythagorean Theorem Proofs - Concept

##### Math›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.
• #### Symmetry of Graphs: Odd and Even Functions - Problem 2

##### Math›Precalculus›Introduction to Functions
How to prove whether a function is even or odd.
• #### Symmetry of Graphs: Odd and Even Functions - Problem 1

##### Math›Precalculus›Introduction to Functions
How to prove whether a function, f(x) = x - 0.04*x^3, is even or odd.
• #### Similar Triangles in Circles and Right Triangles - Concept

##### Math›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.
• #### The Dot Product of Vectors - Problem 3

##### Math›Precalculus›Vectors and Parametric Equations
How to prove that the dot product uu of a vector with itself equals the square of its magnitude abs(u)^2.
• #### Proving Two Functions are Inverses - Problem 3

##### Math›Algebra 2›Inverse, Exponential and Logarithmic Functions
How to use composition of functions to prove that two functions are inverses, including those with domain restrictions.