Multiple Angles and Functions
Up until now, this text has dealt with trigonometric functions of single angles,
and basic trigonometric
identities. In the following
lessons, we'll discuss trigonometric functions of multiple angles, and
identities of multiple trigonometric functions.
When you have a single function and a single angle, calculations are easy. Even
when the angle is a variable, a graph quite easily illustrates how the functions
of the variable angle will behave. Therefore, as we learn formulas for
calculating values of functions of angle sums, products, and sums and products
of different functions, you may wonder why such formulas are necessary or
useful. But the formulas (identities, actually, because they're true for all
angles) we'll learn over the following sections help simplify complicated
double-variable trigonometric equations and thereby allow us to calculate those
double-variable equations through the more simple techniques we've already seen.
With this knowledge, the field of trigonometry will become so wide open, you'll
have to wear shades.
