Question

need an aswer quich ok thiers two the find sin(2pi/3 -pi/4) using sum and difference identites and then tan 5pi/12 using the same identites

Answer 1

You have a formula for

Sin(A-B)

Use that on the first one.

Now on the second, recall that

5PI/12= 3PI/12 + 2PI/12=PI/4 +PI/6

You now can use the tan (A+B) formula, as you know the tan(PI/4) and tan(PI/6)