posted by Rony .
the expression cos4x cos3x + sin4x sin3x is equivalent to
which one of the following is the answer:
Look up the equation for cos(x-y) and it should be obvious what the answer is.
Think of x as 4x and y as 3x.
it is cosx
Seca=4x + 1/x than secb + tana what please tell me after 2days