Page 1 :
‘ ) ), nt about 3-dimensional solids and 2-dimensional st, f closed and open curves were also introduced in pre, chapter, we will define a triangle, quadrilateral, circle etc., , LE CLOSED CURVES, Aclosed curve, which does not cross itself is called a simple closed, Look at the following curves :, , ae Or Oy OL ()}, ) .<, , = o> The. Oo, Bs m, , The starting point for drawing each of the above curves is marked as, black dot., , How many curves cross themselves "tg, , How many curves are open ?, , How many curves are closed ?, , Now look at the following simple closed curves :