We know the following:
sin(x) * cos(x) * tan(x)/sin(x) * cos(x) * tan(x)
Everything cancels and we are left with 1
- csc(x) = 1/sin(x)
- sec(x) = 1/cos(x)
- cot(x) = 1/tan(x)
sin(x) * cos(x) * tan(x)/sin(x) * cos(x) * tan(x)
Everything cancels and we are left with 1