Final answer:
The radius of Neptune is 24,621 km.
Step-by-step explanation:
In mathematics, the radius of a circle is the distance from the centre of the circle to any point on its circumference. It is a fundamental measurement used in geometry To find the radius of Neptune, we can set up an equation using the given information:
Radius of Earth = 6378.1 km
Radius of Neptune = Radius of Earth + 18,243.9 km
So, Radius of Neptune = 6378.1 km + 18243.9 km
Simplifying, we find that the radius of Neptune is 24,621 km.