Mathematics

This is about understanding which trig functions are positive or negative in each quadrant of the coordinate plane. When an angle lands between 90° and 180°, its terminal side sweeps through the second quadrant, where points have negative $x$-coordinates but positive $y$-coordinates. Since $\cos \theta$ corresponds to the $x$-coordinate and $\sin \theta$ to the $y$-coordinate, you get negative and positive values respectively—no calculation needed, just visualize where the angle points.

This is about understanding which trig functions are positive or negative in each quadrant of the coordinate plane. When an angle lands between 90° and 180°, its terminal side sweeps through the second quadrant, where points have negative $x$-coordinates but positive $y$-coordinates. Since $\cos \theta$ corresponds to the $x$-coordinate and $\sin \theta$ to the $y$-coordinate, you get negative and positive values respectively—no calculation needed, just visualize where the angle points.