5.5 Analytic Trigonometry - Double Angles

Trigonometric double angle formulas can be used to find the exact value of an unknown trigonometric function.

NOTE:

 

Deriving the double angle formulas for the 3 trig functions (sin, cos, tan) is simple. We just have to recall our sum and difference formulas.

SIN

 

COS

Also...

*Pick which Cosine formula to use depending on the information you have in the problem :)*

TAN

SAMPLE PROBLEM

FIND: sin2β