- #1
Zetison
- 35
- 0
Homework Statement
Find an albebraic expression for cos((1/3)*arccos(x)), in order to get rid of the trigonometric operands.
Homework Equations
cos(arccos(x))=x
The Attempt at a Solution
cos(x)= 4cos(x/3)^3 - 3cos(x/3), I can reduce cos(cos(x)/3)
by noting that cos(arccos(x))=x. Then I solve the cubic:
1 = 4y^3 - 3y
This was a tips I have found, but, it gave me nothing :P
Need help!