Question 199298
I'll do the first one to get you started. Note: I'll use {{{pi}}} for 3.14



{{{cos(2pi-A)=cos(A)}}} Start with the given equation.



{{{cos(2pi)cos(A)+sin(2pi)sin(A)=cos(A)}}} Expand



{{{(1)cos(A)+(0)sin(A)=cos(A)}}} Evaluate the cosine of {{{2pi}}} to get 1. Evaluate the sine of {{{2pi}}} to get 0



{{{cos(A)+0=cos(A)}}} Multiply



{{{cos(A)=cos(A)}}} Simplify



So this verifies the identity.