%% () Calculates the difference (in x and y components of a vector in m) between destinations resulting from two different compass bearings.

%% Calculates the formula for a shape's property based on trigonometry
/**
c2 =(b-x)2 +h2, and a2 =x2 +h2
so that c2	-	(b-x)2	= h2	and a2	– x2	= h2
By the transitive property c2 - (b-x)2 = a2 – x2
Expanding (b-x)2
c2	– b2	+ 2bx – x2	= a2	– x2
c2	= a2	+ b2 – 2bx
Figure 2
Now eliminate x from the equation by substituting a value of x which involves the cosine of C.
CosC = x/a-----> x = aCosC c2=a2 +b2 –2b(aCosC) c2=a2 +b2 –2abCosC
**/

%% Calculates a list of right-angle triangles from a chart

%% chart_to_ratl([D,E,F],[[C,D,E],[A,E,F],[

%% chart_to_ratl(+Points,+Relations,+RightAngles,-RightAngleTriangles)
%% Points -  e.g. D, E, F, G around a shape
%% Relations - e.g. list of [C, D, E], in which C is the line label, for the line between points D and E
%% RightAngles - e.g. list of [D, G, E], in which there is a right angle between D, G and E
%% RightAngleTriangles - e.g. list of [D, G, E], in which D, G and E form a right-angle triangles.

chart_to_ratl(Points,Relations,RightAngles,RightAngleTriangles) :-