question: private double findAngle ( Point originPoint , Point targetPoint ) { int x1 = originPoint . x ; int y1 = originPoint . y ; int x2 = targetPoint . x ; int y2 = targetPoint . y ; double angle = 0.0 ; double offset = 0.0 ; double sideA = x2 - x1 ; double sideB = 0.0 ; if ( y1 >= y2 ) { sideB = y1 - y2 ; offset = Math . toRadians ( - 90 ) ; } else { sideB = - ( y2 - y1 ) ; offset = Math . toRadians ( 90 ) ; } if ( sideB == 0 ) { return angle ; } angle = Math . atan ( sideA / sideB ) ; return angle + offset ; }
target:  uses trig to find angle of the arrow