Question 181640
This is a typical right triangle problem, how should you know:

(1) Draw a figure:  the pole must be straight up (leg of triangle), from the bottom of the pole to the point where the wire will connect to the floor is another leg of triangle, and the wire is slanted from top of pole to floor.

(2) You use pythagorean theorem to solve problems where (a) it is a right triangle, (b) you know two side's lenghts of the triangle and need to find missing side length.
a^2 + b^2 = c^2  ; where c is the longest side (hypoteneus, accros from 90 degree angle)

ANSWER:

a^2 + b^2 = c^2
(8)^2 + b^2 = (12)^2
64 + b^2 = 144
64-64 + b^2 = 144 - 64
b^2 = 80
sqr(b^2)= sqr(80)
b= sqr(80)
b= sqr(16*5)
b=sqr(16)* sqr(5)
b= 4sqr(5)

where sqr means square root