Please answer the following question?

(a) sin(3x) = sin(2x+x)
      = sin(2x)cos(x) + cos(2x)sin(x)
      = 2sin(x)cos^2(x) + (1-2sin^2(x))sin(x)
      = 2sin(x)(1-sin^2(x)) + (1-2sin^2(x))sin(x)
      =3sin(x) - 4sin^3(x)


(b)
csc(A) = 1/sin(A)
csc(π/3-A) = 1/sin(π/3-A)
    = 1/(sin(π/3)cos(A) - cos(π/3)sin(A))
    = 1/(√3 cos(A)/2 - sin(A)/2)
csc(π/3+A) = 1/(√3 cos(A)/2 + sin(A)/2)

csc(A) + csc(π/3-A) - csc(π/3+A)
    = 1/sin(A) + sin(A)/(3cos^2(A)/4 - sin^2(A)/4)
    = 1/sin(A) + sin(A)/(3/4 - sin^2(A))
    = (3/4 - sin^2(A) + sin^2(A)/[(3/4)sin(A) - sin^3(A))
    = 3/(3sin(A)-4sin^3(A))
    = 3/sin(3A)
    = 3csc(3A)