Question 918951
i ran out of time but i think this is the correct answer.
check it out and see if you agree.
i graphed it and it looks ok but i don't have the time to extensively test it, although i'm pretty sure it's what you need.


basic definition is that y = cos(x) if and only if x = arc-cosine(y)


in your problem, you would use this as follows:


start with 25y = 5 * cosine(3x-6)


divide both sides of the equation by 5 to get:


5y = cosine(3x-6)


this is true if and only if arc-cosine(5y) = 3x - 6


add 6 to both sides of the equation to get:


arc-cosine(5y) + 6 = 3x


divide both sides of the equation by 3 to get:


x = (arc-cosine(5y) + 6) / 3


that should be your solution.


i tested it on 5y = 1/2


if 5y = 1/2, then arc-cosine (5y) = 60 degrees.


can't continue.


i have to leave now.


if you have further questions on this send them to me and i'll look at them later this evening or tomorrow morning.