• #### The Cosine Addition Formulas - Concept

How to derive the cosine of a difference formula.
• #### The Half-Angle Identities - Problem 1

How to use a half-angle formula to evaluate sin(/8).
• #### The Inverse Cosine Function - Problem 3

How to graph a simple transformation of y = cos^-1(x) + pi/2
• #### The Inverse Cosine Function - Concept

How to restrict the domain of cosine so it will have an inverse function.
• #### Solving Trigonometric Equations - Concept

How to solve a simple sine equation: sin (theta) = 1/2.
• #### Angle Inclination of a Line - Problem 2

How to find the angle of inclination of a line.
• #### Solving Trigonometric Equations - Problem 2

How to solve a simple tangent equation: tan(x/4)=1.
• #### Using the Inverse Trigonometric Functions - Problem 2

How to find an algebraic expression that is equivalent to sec2(tan-1 x).
• #### Using the Inverse Trigonometric Functions - Concept

How to evaluate expressions like tan(sin (4/5))^(-1).
• #### The Cosine Addition Formulas - Problem 2

How to derive the cosine of a sum formula and use it to find the cosine of an angle.
• #### Solving Trigonometric Equations - Problem 1

How to solve a simple cosine equation: cos x = ?2/2.
• #### Solving Trigonometric Equations - Problem 3

How to solve a simple trig equation involving secant.
• #### Using Sine to Calculate the Area of a Triangle - Concept

##### Math›Trigonometry›Basic Trigonometry
How to calculate the area of any triangle using two sides and an included angle.
• #### Using Sine to Calculate the Area of a Triangle - Problem 1

##### Math›Trigonometry›Basic Trigonometry
How to calculate the area of a triangle using two sides and an included angle.
• #### The Sine Addition Formulas - Problem 3

How to evaluate sin(a ? b) and sin(a + b) when you know only cos(a) and sin(b).
• #### The Double-Angle Formulas - Concept

How to use the sine and cosine addition formulas to prove the double-angle formulas.
• #### The Double-Angle Formulas - Problem 1

How to use the sine and cosine double-angle formulas to find sin(2a) and cos(2a) when sin(a) is known.