Answer and explanation:
The connection of the rope from the stake to the pole will form a triangle so that one side is the hypotenuse(the rope), another is the opposite side(the pole) and the other is the adjacent side(the distance from the stake to the pole).
The unknown side is the adjacent side which is the distance from the stake to the pole. To find an unknown side in a triangle in this form, we use the Pythagorean theorem.
Therefore c²=a²+b²
c=20ft
a= 7ft
b= unknown
So we use the formula to find unknown side(distance from stake to base of pole)
20²=7²+b²
400=49+b²
b²=400-49
b²= 351
b=√351
b= 18.735ft
Therefore distance from stake to base of pole = 18.735 feet