I know the equation for cos 2x but this doesn't help - I get $\displaystyle 2cos^2(3x/2) - 1$ which doesn't really help. Is there any other way which it can be done?
I know the equation for cos 2x but this doesn't help - I get $\displaystyle 2cos^2(3x/2) - 1$ which doesn't really help. Is there any other way which it can be done?
Sure db5vry,
express Cos(3x) as Cos(2x+x)
expand this using Cos(A+B) and expand Cos(2x) later using Cos(x+x).