7.1 Trigonometric functions
You’ve probably come across the following formulae:11 1 Often remembered using the sort-of mnemonic ”SOH-CAH-TOA” (i.e. ”COS=OPPOSITE/ADJACENT, COS=ADJACENT/HYPOTENUSE, TAN=OPPOSITE/ADJACENT).
The way we work out the actual values of , and is by making things as easy as possible for ourselves; we draw a triangle inside a circle with radius one. From here, we know that
Note that because this is the unit circle, we have
And if we substitute and we get that
Below you can find high-precision, to-scale plots of the graphs 33 3 Protip: learn how to draw the graphs without having to thtink about it! of both and as well as a diagram of the unit circle.