difference in latitude problem

[n0limit5]

Assuming that Earth is a sphere of radius 6378 kilometers, what is the difference in the latitudes of Lynchburg, Virginia, and Myrtle Beach, South Carolina, where Lynchburg is 400 kilometers due north of Myrtle Beach?

So far i have drawn a circle with a radius of 6378km and a line from the center to half the circle with a distance of 400km. One pt is Lynchburg and another pt is Myrtle Beach. Help please i deeply dont understand this problem, the book doesn't should how to do it.

 

[tkhunny]

You need a nice LONG isosceles triangle - with a little ice cream cone sticking out of the top.

The two matching sides are 6378 kilometers.
The arch of the ice cream cone is 400 kilometers.

Your task is to find the angle between those two giant triangle legs.

Hint:
Arch: \(\displaystyle 400\)
Circumference: \(\displaystyle 2*\pi*6378\)

I used to live in Lynchburg!