What is the distance to the earth’s horizon from point P?

Answer:
156.7 miles.
Step-by-step explanation:
The radius and the tangent at the point of contact form a right angle so we can apply the Pythagoras theorem:
( 3959 + 3.1)^2 = x^2 + 3959^2
x^2 = 3962.1^2 - 3959^2
x^2 = 24555.41
x = 156.7 miles.