I've just begun learning how to use identities to evaluate the exact trig values of various angles. The issue is that some angles cannot easily be reduced to the sum, difference, half or double of any combination of reference angles. How may I go about computing these exact values by hand? If it is possible but so infrequently required that I am unlikely to need to know it for a highschool test then that is a suitable answer. Thanks in advance.
It would help if you gave a clear example of what exactly you want. All trig. angles can be found given some variables such as length of one side and one angle....etc., by using the sine, cosine, tangent relationships. So, an example would be an excellent place to start. Good luck.
Some examples are the angles 84, 73, 21, 91, 17 and 6. I know that all of them can be found exactly, but I know that many of them seemingly can't be evaluated using the identities for sum, difference, half and double angles.
Hi There: Don't worry about sums, differences.....etc. The most important thing in Trig. are the ratios between the legs of the triangle, i. e., sine, cosine and tangent. For example, in a right-angle triangle, if you give me an angle and the length of one side, I can find the values of ALL angles and ALL three sides.
