Move one of the vertices of the quadrilateral ABCD. Observe What is happening.... What is your conclusion?
Use the above applet and check whether the property is true for any convex quadrilateral?
Can 35[math]^\circ[/math] , 65[math]^\circ[/math], 125[math]^\circ[/math] and 130[math]^\circ[/math] be the angles of a quadrilateral? Justify your answer