类别 全部 - triangles - angles - positive - ratios

作者:Williams Shireece 4 年以前

283

Trigonometric Ratio

Trigonometric functions are essential in understanding angles and their relationships within different quadrants. Each quadrant in the coordinate system has specific trigonometric ratios that are positive.

Trigonometric Ratio

Trigonometric Ratio

The CAST rule

C Quadrant
cosθ and secθ will be positive
A Quadrant
All trigonometric ratios and their corresponding reciprocal functions are positive.
T Quadrant
tanθ and cotθ will be positive
S Quadrant
sinθ and cscθ will be positive.

The special triangles

How to sketch an angle

Terminal Arm: the ray the defines the end of the angle
Initial Arm: the ray that defines the beginning of the angle.

An example

tan(11π/6)= -tan(π/6)= -1/√3
sec (5π/4) = -sec(π/4)= -√2