Answer:
5√5 ≈ 11.18 units
Step-by-step explanation:
The Pythagorean theorem can be used to find the unknown leg of a triangle with hypotenuse 15 and one leg 10:
d = √(15^2 -10^2) = 5√(3^2 -2^2) = 5√5
The plane is 5√5 units from the center of the sphere.