Answer:
16.2 m
Explanation:
First, we can draw a picture. The cable goes from the top of the pole to the ground (with the pole on the right in my drawing), and the point on the ground is 10 m away from the base of the pole. This forms a right triangle, with the right angle being between the 10 m distance and the pole itself. We can then apply the Pythagorean Theorem, so
a²+b²=c², with c being the side opposite the right angle (the cable), getting us
10²+(length of pole)² = 19²
19²-10²=(length of pole)²
= 261
square root both sides to isolate the length of the pole
length of pole ≈ 16.2 m