Graph the following from X = 0 to x = 2 pi
2cos 6x cos4x + 2 sin 6x sin 4x
You can only graph "equations" that are written in the form y = ... or f(x) = ....
are you graphing y = 2cos 6x cos4x + 2 sin 6x sin 4x ?
this reduces to y = 2cos(6x-4x)
y = 2cos 2x
If you are studying this topic you should be able to sketch this one quite readily.