Trigonometry Functions Chart - Great reference for Precalculus Students and Teachers. It includes all the major functions of sin, cos, and tan. It even includes the reciprocal functions of csc, sec, and cot.
In pre-calculus, the unit circle is sort of like unit streets, it’s the very small circle on a graph that encompasses the coordinates. It has a radius of hence the unit. The figure here shows all the measurements of the unit circle: