Primary Trigonometry Functions

Sine (sin)
Cosine (cos) and
Tangent (tan)

The first thing that come to mind when I hear these is: equation. I like to define these as equations or formulas for solving specific angles or line segments in a right angled triangle. You can remember these things by remembering soh-cah-toa (so - ka - toe - ah, you'll find out what I means as I go through them).

Sine
The abbreviation for sine is sin (not sin like in you did something bad but, sin like a stop sign, you still pronounce it like sine). The equation/formula for this is sin('theta')=opposite/adjacent (don't worry I'll have examples). You can remember sine my remembering the soh in sho-cah-toa, meaning s=o/h so sine equals opposite divided by hypotenuse.

Cosine

The abbreviation for cosine is cos. The equation/formula for this is

cos('theta)=adjacent/hypotenuse. You can remember cos by remembering the cos in soh-cah-toa, meaning c=a/h so cos equals adjacent diveded by hypotenuse.

Tangent

The abbreviation for tangent is tan. The equation/formula for this is

tan('theta')=opposite/adjacent. You can remember tan by remembering the toa in soh-cah-toa, meaning t=o/a so tan equals opposite divided by adjacent.

ex) say we have a (right angled) triangle with the opposite as 3 and theta as 48degrees. Solve for adjacent.

tan'theta'=o/a

tan48=3/a

tan48(a)=3

tan48(a)/tan48=3/tan48

a=2.7012...