# the cosine double angle formulas   187 videos

• #### Area of Regular Polygons

##### GeometryArea

How to derive the formula to calculate the area of a regular polygon.

area apothem side hexagon isosceles triangle perimeter equilateral equiangular
• #### Area of Circles

##### GeometryArea

How to derive the formula to calculate the area of a circle.

• #### Surface Area of Cylinders

##### GeometryArea

How to prove the surface area of a cylinder formula.

circle lateral area circumference
• #### Area and Perimeter of Rectangles

##### Pre-AlgebraIntroductory Geometry

Overview of area and perimeter formulas for parallelograms and rectangles

• #### Volume and Surface Area

##### Pre-AlgebraIntroductory Geometry

Vocabulary and formulas for surface area and volume of common solids

• #### Exponential Growth and Decay

##### Algebra 2Inverse, Exponential and Logarithmic Functions

How to use the exponential growth and decay formula.

exponential growth exponential decay
• #### Recursion Sequences

##### Algebra 2Sequences and Series

How to use a recursion formula to represent the Fibonacci sequence.

recursion previous term Fibonacci
• #### Recursion Sequences

##### PrecalculusSequences and Series

How to use a recursion formula to represent the Fibonacci sequence.

recursion previous term Fibonacci
• #### Using the Inverse Trigonometric Functions

How to evaluate expressions like tan(sin (4/5))^(-1).

sine cosine tangent inverse sine inverse cosine inverse tangent the unit circle
• #### Using the Inverse Trigonometric Functions

How to evaluate expressions like tan(sin (4/5))^(-1).

sine cosine tangent inverse sine inverse cosine inverse tangent the unit circle
• #### Similar Triangles

##### Pre-AlgebraIntroductory Geometry

Overview of similarity: congruent angles, proportional corresponding sides

• #### The Tangent Function

##### TrigonometryTrigonometric Functions

How to define the tangent function for all angles.

tangent right triangle trigonometry the unit circle
• #### The Tangent Function

##### PrecalculusTrigonometric Functions

How to define the tangent function for all angles.

tangent right triangle trigonometry the unit circle
• #### Using Trigonometric Identities

##### PrecalculusTrigonometric Functions

How to simplify a trigonometric expression by converting to sines and cosines and using algebra.

reciprocal identities
• #### Using Trigonometric Identities

##### TrigonometryTrigonometric Functions

How to simplify a trigonometric expression by converting to sines and cosines and using algebra.

reciprocal identities
• #### Trapezoid Properties

##### GeometryPolygons

How to identify a trapezoid and its special properties.

parallel sides isosceles trapezoid base angles base
• #### The Product Rule

##### CalculusTechniques of Differentiation

How to differentiate a product of two functions.

differentiation derivative formula power functions the product rule of derivatives
• #### Kite Properties

##### GeometryPolygons

How to identify a kite and its special properties.

kite diagonals consecutive sides vertex angle non vertex angle bisect perpendicular
• #### Area of Parallelograms

##### GeometryArea

How to find the area of any parallelogram using rectangle area formulas.

area of rectangles base times height
• #### Area of Trapezoids

##### GeometryArea

How to derive the area of a trapezoid formula using the area of a rectangle.

trapezoid parallelogram base height