The How and Why of Mathematics | How to get trig identities from the unit circle @THaWoM | Uploaded 5 years ago | Updated 3 hours ago
A lot of trigonometric identities don't need to be memorised - you can derive them on the fly using the unit circle. I'll be covering sin(180 + x) = -sin x, cos(-x) = cos x, etc, as well as cos^2 x + sin^2 x = 1 and equations you can derive from it, sin(90-x) = cos(x) etc, and the various ways of expressing cot. In this video we'll also start to use radians.

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