How to Solve Using Trigonometric Identities


Cofunction identities are relatively simple. People tend to see big words and immedialtely assume that it's more complicated than it is. It makes them feel important. Once you see past this, it really is simple.
When you looked at the unit circle, did you notice that a lot of the same numbers where used? In fact, we only use 6 numbers on the entire unit circle, not counting negatives.  This means that there has to be a lot of numbers repeated through out our answers. This is math, so there has to be a pattern to those repetitions. COfunction Identities name that pattern, using the math terminology. In real-people terms, when sine is at  30 ° , it equals 1/2. COsine is 1/2 at 60 °. See the similarity? This is true of all functions and their CO-functions, like secant and COsecant, tangent and COtangent. This is why we have cosine as supposed to ferugson for a trig function. So the identities are as follows: