Answer:
The correct answer is the last option.
Step-by-step explanation:
When you have a fraction with complex numbers, the first step to simplify is to multiply up and down the conjugate of the denominator, this will eliminate the complex part of the denominator, and in this way you can separate the expression in its real and complex part.
For the expression:

The denominator conjugate is 4 + 2i
When multiplied, the denominator is:

Answer:
39.407m
Step-by-step explanation:
sin 66deg = 36/length of cable
length of cable = 36/sin 66deg = 39.407m (5sf)
First we know that:
AB+BC=AC
now , since B is the midpoint of AC, this means that AB=BC
therefore,
AB+BC=AC can also be written as
AB+AB=AC
3x-1+3x-1=8x-20
6x-2=8x-20
-2+20=8x-6x
18=2x
x=9
therefore:
AB=3(9)-1=27-1=26
AC=8(9)-20=52
BC=AB=26
128/100=32/25
..................