A and B points are given on the globe $($r$=6370$ km$).($The latitude of point A is $36$ degrees and the longitude is $37$ degrees.

Point B has a latitude of $36$ degrees and a longitude of $41$ degrees.$)$

Please compute;

a$.$ The distance of the arc between these two points on the latitude of $36$ degree

in distance unit

b$.$ The spherical distance between these two points in distance unit