• #### Concept

##### Science›Chemistry›Chemical Reactions
Understanding the differences between empirical and molecular formulas.
• #### The Double-Angle Formulas - Concept

How to use the sine and cosine addition formulas to prove the double-angle formulas.

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

How to use the sine and cosine addition formulas to prove the double-angle formulas.

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• #### The Double-Angle Formulas - Problem 2

How to derive a triple-angle formula for cosine.
• #### The Double-Angle Formulas - Problem 2

How to derive a triple-angle formula for cosine.
• #### Solving Formulas - Concept

##### Math›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.
• #### Using the Sine and Cosine Addition Formulas to Prove Identities - Problem 3

How to use the sine and cosine addition formulas to prove a difference formula for tangent.
• #### Using the Sine and Cosine Addition Formulas to Prove Identities - Problem 3

How to use the sine and cosine addition formulas to prove a difference formula for tangent.
• #### The Sine Addition Formulas - Concept

How to derive the sine of a sum formula.
• #### The Cosine Addition Formulas - Concept

How to derive the cosine of a difference formula.
• #### The Cosine Addition Formulas - Concept

How to derive the cosine of a difference formula.
• #### The Euler Formula - Problem 3

##### Math›Precalculus›Polar Coordinates and Complex Numbers
How to derive two trigonometric identities using Euler's Formula.
• #### The Sine Addition Formulas - Concept

How to derive the sine of a sum formula.
• #### Other Forms of the Cosine Double-Angle Formula - Problem 1

How to use the cosine double-angle formulas to derive the power reduction formulas.