The midpoint of the points ( 4, 5.5 ) and ( 4, 10.5 ) is the center of the circle:
C =

C = ( 4, 8 ), h=4, k=8
r =

r = 2.5
The equation of the circle in standard form:
( x - h )² + ( y - k )² = r²
( x - 4 )² + ( y - 8 ) = 6.25
Answer:
Rock travels about 8.2x²meters higher on the moon than on the Earth.
Step-by-step explanation:
Expression showing the height of a rock thrown into the air at Earth is,
f(x) = -9.8x² + 10x + 1.5
Similarly, expression showing the height of rock thrown on the moon is,
g(x) = -1.6x² + 10x + 1.5
Difference in the height of the rock thrown on moon = g(x) - f(x)
= (-1.6x² + 10x + 1.5) - ( -9.8x² + 10x + 1.5)
= -1.6x² + 9.8x² + 10x - 10x + 1.5 - 1.5
= 8.2x²
Therefore, rock travels about 8.2x²meters higher on the moon than on the Earth.