Trigonometric Functions
Functions
There are 6 main functions of trigonometry. I completely confused and never understood these. The simplest explanation that I watched was Dennis Davis' video. These notes serve as notes for that video.
The mnemonic tool to memorizing the 6 trig functions is: SOH-CAH-TOA
- SOH = Sine Opp/Hyp
- CAH = Cosine Adj/Hyp
- TOA = Tangent Opp/Adj
To understand the references of these, this image helps
The short-forms stand for: Opp = Opposite, Hyp = Hypotenuse, Adj = Adjacent (to the angle)
Common way to represent the angle is: \displaystyle \theta and the common way to represent the functions are: \displaystyle sin\theta, cos\theta, tan\theta
So, the overall 6 functions are:
\displaystyle sin\theta is Opp/Hyp
\displaystyle cos\theta is Adj/Hyp
\displaystyle tan\theta is Opp/Adj
\displaystyle csc\theta is Hyp/Opp (Inverse of Sine)
\displaystyle sec\theta is Hyp/Adj (Inverse of Cosine)
\displaystyle cot\theta is Adj/Opp (Inverse of Tangent)
Most of the concepts here are quite a prerequisite for Gradient Descent and ML math in general, so this is "foundational" level for it.