Step-by-step explanation:
[tex] \cos(a) + 2 \cos(a + 240) [/tex]
[tex] \cos(a) + 2 \cos(a) \cos(240) - \sin(a) \sin(240) [/tex]
[tex] \cos(a) + 2( - \frac{ \cos(a) }{2} + \frac{ \sqrt{3} }{2} \sin(a) )[/tex]
[tex] \cos(a) - \cos(a) + \sqrt{3} \sin(a) [/tex]
[tex] \sqrt{3} \sin(a) [/tex]
If you graph the new identity, and the og identiy, they will be conciding graphs, so they are the same identity.
