question: private float sweep ( float tan1X , float tan1Y , float tan2X , float tan2Y ) { final float minorSweep = ( float ) Math . toDegrees ( 2 * ( Math . asin ( .5 * Geometry . distance ( tan1X , tan1Y , tan2X , tan2Y ) / mScaledTouchSlop ) ) ) ; return 360 - minorSweep ; }
target:  Find the angle in degrees between two tangent points