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MATHEMATICS

Measure the size of an angle


Can someone tell me what series of instructions are necessary to determine the size of an angle in degrees or brads or radians or grads given the points which determine a line. For instance if I have a line with endpoints X1,Y1 and X2,Y2 how do I determine the angle this line makes with either the X or Y axis. Certainly I can determine the slope of the line and even the trig functions such as SIN, COS, TAN etc, but how do I determine the size of the angle in degrees or brads or radians or grads.

Dale Blackwell

I use CALL GETMOUSE() and WHILE FN BUTTON to determine starting and ending positions of the mouse and draw a line between these points.

If X1,Y1 and X2,Y2 are these point coordinates, imagine a triangle with the abovementioned line as one side and two other sides, one vertical, one horizontal.

Size of horizontal side :
CoteAdj% = ABS(X2 - X2)
Size of vertical side :
CoteOpp% = ABS(Y2 - Y1)
The angle in radians is :
AngleRad# = ATN(CoteOpp%\CoteAdj%)
and in degrees :
AngleDeg# = (AngleRad# * 360.0) \ (2.0 * 3.14159)
Patrick