You are introduced to the trigonometric sum and difference (addition) identities sin(A ± B), cos(A ± B) and tan(A ± B) which you should try and learn. These are used to prove more further trig identities and in the solution of equations.

You are introduced to the trigonometric sum and difference (addition) identities sin(A ± B), cos(A ± B) and tan(A ± B) which you should try and learn. These are used to prove more further trig identities and in the solution of equations.