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.
Calculus for Beginners and Artists is an online textbook that provides an overview of Calculus in clear, easy to understand language designed for the non-mathematician. Thank you MIT OpenCourseWare for awesome, free resources and classes!