how to solve the questions (b) and (c)

Q20. Complex Trigonometric. Express the following in cartesian form a + ib with a, b real. cos(0) + i sin(0 (a) (cos(0) + i sin(0)) (cos(0) - i sin(0)) (b) cos(Q) + isin(d 1 [Hint for (b) and (c): Multiply by the ( c ) 1 + cos(a) + isin(a) conjugate of the denominator