Angle between traces formed by four geografic coordinates

Question

enter image description hereIf I have a first trace formed by two coordinates:

lat1=-2.760411024093628
lat2=-2.799418926239014
long1=-12.332500457763672
long2=-12.508299827575684

and a second trace of the coordinates:

lat3=-2.799418926239014
lat4=-2.838399887084961
long3=-12.508299827575684
long4=-12.684100151062012

how can I calculate the small geographic angle between the two traces? I would like to apply in some calculation on MATLAB code. I was in double to calculate also

thanks, Guilherme

I was trying to calculate using the form: a = atan2d(x1y2-y1x2,x1x2+y1y2);

but it does not works.