Cosine: cos30 degrees = two-thirds of the root.

Sin45 degrees = two-thirds root sign.

Cos45 degrees = two-thirds root sign

Sin60 degrees = two thirds root number three

Cos60 degrees = 1/2

Sin90 degrees = 1

Cos90 degrees =0

Sin 120= two thirds root number three

Cos 120 degrees = negative 1/2.

Sin 135= two-thirds root sign.

Cos 135 degrees = minus two thirds.

sin 150= 1/2

Cos 150 degrees = minus two thirds root number three.

sin 180=0

Cos 180 degrees = negative 1

Tangent: tan30 degrees = the root of three.

Tan45 degrees = 1

Tan60 degrees = root number 3

Tan90 degrees =/(meaningless)

Tan 120 degrees = minus three.

Tan 135 degrees = negative 1.

Tan 150 degrees = minus two thirds.

Tan 180 degrees =0

Cotangent is the reciprocal of tangent.

If the back tangent is behind, it is suggested to draw a triangle (internal angles 30, 60, 90). After learning the quadrant distribution, the tangents of the first and third quadrants are positive, and the second and fourth quadrants are negative.

If you recite sine and cosine, it is recommended to draw trigonometric function image memory.