Let M be arbitrary points on a semi-circle center O, DK AB = 2R (M # A, B). Draw the tangent Ax, By, cut half circles that Mz. Mz road cut Ax, By in N, P. By cutting a straight line at C AM, BM cut in D. Ax
C / m: line 3 BA, PN, CD contract rules
thanks you very much, do it quickly and I heard Dum!