Trigonometric Ratios of Rotation and Reference Angles的副本

Modify the value of the rotation angle by moving the angle slider or typing the value in the text box. Remember that: (a) the rotation angle is positive (negative) when OA is rotated in anti-clockwise (clockwise) direction. (b) sinθ=y/x, cosθ=x/r, tanθ=y/x (x ≠ 0), where r= sqrt (x^2+y^2) (c) r is always larger than 0 (d) the CAST diagram. You can easily memorise it by saying "All Students Take Chinese." Amended by Sit Hon Yip