Arccos problems

[Loki123]

So usually when I would use arccos, arcsin I'd have two answers. One that's just arccos x and one that is pi - arccos x. In this case the solution only had one. Why?

 

[Harry_the_cat]

What if you had $\displaystyle \cos x =\frac{1}{2}$, what would your solution be?

Could you post the whole question please?

 

[blamocur]

$x=\arccos a$ is a solution of the $\cos x = a$ equation, but $\pi - \arccos a$ is not -- you might be confusing it with $\arcsin$ case.

 

[Deleted member 4993]

So usually when I would use arccos, arcsin I'd have two answers. One that's just arccos x and one that is pi - arccos x. In this case the solution only had one. Why? View attachment 30976

Was there a specified domain?

The second answer could be:

x = 2*pi - (3-y)/(2*y)