This week in precalc 11 i learned about the cast rule  

 

The cast rule show where each ratio is positive 

 you can you the phrase “All students take calculus” to remember where the ratio’s are positive

Let’s say your calculator gives you 82 degrees from cos 35 

One may think that because the calculator gives you one answer in quadrant 1, that is the only answer. However, you must be smarter than your calculator to realize it can also be in a different quadrant. 

 

Looking at the CAST rule, a positive 82 degrees can be also found in Q4 

Therefore, we can take the 360 and minus 82 to get an angle of 278 degrees. 

 

So, there can be more angles shown without your calculator that you need to be able to do