Distance between two points on the Moon Given latitude/longitude of two points on the Moon (lat1, lon1) and (lat2, lon2), compute the distance between the two points in kilometers, by using any formula that gives the same result as the haversine formula.
Input

Four integer values lat1, lon1, lat2, lon2 in degree (angle) or
four decimal values ϕ1, λ1, ϕ2, λ2 in radians.

Output
Distance in kilometers between the two points (decimal with any precision or rounded integer).
Haversine formula

where

r is the radius of the sphere (assume that the Moon's radius is 1737 km),
ϕ1 latitude of point 1 in radians
ϕ2 latitude of point 2 in radians
λ1 longitude of point 1 in radians
λ2 longitude of point 2 in radians
d is the circular distance between the two points

(source: https://en.wikipedia.org/wiki/Haversine_formula)
Other possible formulas

d = r * acos(sin ϕ1 sin ϕ2 + cos ϕ1 cos ϕ2 cos(λ2 - λ1)) @miles'  formula.
d = r * acos(cos(ϕ1 - ϕ2) + cos ϕ1 cos ϕ2 (cos(λ2 - λ1) - 1)) @Neil's  formula.

Example where inputs are degrees and output as rounded integer
42, 9, 50, 2  --&gt; 284
50, 2, 42, 9  --&gt; 284
4, -2, -2, 1  --&gt; 203
77, 8, 77, 8  --&gt; 0
10, 2, 88, 9  --&gt; 2365

Rules

The input and output can be given in any convenient format.
Specify in the answer whether the inputs are in degrees or radians.
No need to handle invalid latitude/longitude values
Either a full program or a function are acceptable. If a function, you can return the output rather than printing it.
If possible, please include a link to an online testing environment so other people can try out your code!
Standard loopholes are forbidden.
This is code-golf so all usual golfing rules apply, and the shortest code (in bytes) wins.
Wolfram Language (Mathematica), 48 bytes

ArcCos[Sin@#*Sin@#3+Cos[#2-#4]Cos@#*Cos@#3]1737&amp;


Try it online!

Uses the formula d = r * acos( sin ϕ1 sin ϕ2 + cos ϕ1 cos ϕ2 cos(λ2 - λ1) ) where r = 1737