Answer:
True
Explanation:
Angles in the Cartesian plane move from x-axis to an anticlockwise direction to give positive angles
When angles are formed through clockwise movement they fall on the Fourth quadrant ....in the fourth quadrant only Cosine is positive meaning Sin and Tan are negative hence
tan(-20°) = -tan 20°
In a summary
cos(-a)= cosa
tan(-a) = -tana
sin(-a) =-sina