How about this,
taking the cosine inverse of -1 will get me 180, that is obtuse. so i take the acute angle of it that is 0. And it is equals to cosine inverse of 1.
So this shows that whenever u sin cos tan something and get the obtuse angle, just use the acute angle? am i right?
- To find the angle between and if is negative (say, ), find the acute angle whose cosine is and subtract it from .
- This works in exactly the same with with . If is negative, find the angle whose tangent is the same positive number, and subtract from .
- With , there are no negative values between and : and have exactly the same positive value. You need angles outside this range if you want negative values of sine. For instance, if , then you can find the acute angle whose sine is and either add this to or subtract it from .
I told you that, sadly, it wasn't as simple as you were trying to make it!