Use the formula for cos(alpha+beta), and use numeric values for sin(300°) and cos(300°).Hi, I have the following identity:
cos alpha-2cos(alpha+300) = - square root 3 * sin alpha
I am a bit confused as to where to start
Ok I have solved that one.
b) Hence, determine the maximum value of cos alpha-2cos(alpha+300)
What do they mean by max value?
Sine and Cosine functions are cyclic - that means the functional values repeat with a cycle. For example the maximum value of cos(Θ) is +1 and the minimum value is -1.
That won't help because there are cosines of two different angles, alpha and (alpha+300°).So must I replace cos alpha by 1?
You are saying that the maximum value is a negative number. Does that make sense? Even zero would be bigger than that. The sine can have any value between -1 and +1 (inclusive). Try again. And as I told you before, "Watch out for the - sign."By replacing sin alpha by 1:
-root 3 *1
= -root 3