Terminal side of an angle - trigonometry

In trigonometry an angle is usually drawn in what is called the "standard position" as shown above. In this position, the vertex (B) of the angle is on the origin, with a fixed side lying at 3 o'clock along the positive x axis.

The other side, called the 'terminal side' is the one that can be anywhere and defines the angle. In the figure below, drag point A and see how the position of the terminal side BA defines the angle.

See also Angle definition and properties - Trigonometry

Other trigonometry topics

Angles

• Angle definition, properties of angles
• Standard position on an angle
• Initial side of an angle
• Terminal side of an angle
• Quadrantal angles
• Coterminal angles
• Reference angle

Trigonometric functions

• Introduction to the six trig functions
• Functions of large and negative angles
• Inverse trig functions
• SOH CAH TOA memory aid


• Sine function (sin) in right triangles
• Inverse sine function (arcsin)
• Graphing the sine function
• Sine waves


• Cosine function (cos) in right triangles
• Inverse cosine function (arccos)
• Graphing the cosine function


• Tangent function (tan) in right triangles
• Inverse tangent function (arctan)
• Graphing the tangent function


• Cotangent function cot (in right triangles)
• Secant function sec (in right triangles)
• Cosecant function csc (in right triangles)

Solving trigonometry problems

• The general approach
• Finding slant distance along a slope or ramp
• Finding the angle of a slope or ramp

Calculus

• Derivatives of trigonometric functions