MATLAB: Angle determination between pinned curved line.

angle

How to find out the angle ϕ shown in above figure? line is pinned at different points.

Best Answer

If s1 is the derivative of the curve on the left at the middle point and s2 the derivative of the curve on the right side at the middle point, the upper angle between the two tangent lines to the curves at that point is given in radians by:
 a  =  mod(atan2(s2-s1,-1-s1*s2),2*pi);
To convert the angle to degrees, multiply this by 180/pi.
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