For the first question you have:
You know that the value of the sin function can vary between -1 and + 1 inclusive, yet if you evaluate what do you get?
As for the proof of the sum of angles formula, see: Proof of the sum and difference formulas.
Hey i have some mixed problems i cant get my head around, i was wondering would any of you know the possible solutions to the following:
sin(30-X)=3÷root 2...finding the values between 0 and 360 degrees.
Thank you guys!