What is that sin thing..?

Question

Is it adj over hyp?

What are the rest of the trig functions?

Answer 1

All pertain to a right triangle. The hypotenuse is the longest side of the triangle (across from the 90º angle).

sin of an angle =opposite side length÷hypot length
cos =adjacent÷hypot
tan = opposite÷adjacent (or sine/cosine)

Answer 2

Draw a little right triangle ABC. Call the right angle at point C so that AB is the hypotenuse. Let angle A be your angle of interest.
Sin A = opposite side (BC)/hypotenuse(AB)
Cos A= adjacent side (AC)/hypotenuse (AB)
Tan A= opposite side(BC)/adjacent side(AC)
The co-functions, cosecant A, secant A, and cotangent A are the reciprocals of sin, cos and tan respectively.