An ellipse is the set of points in a plane that have the sum of their distances from two points a constant. 
		Each of the fixed point is called focus. They are the foci of the ellipse.
   	               With the center at the origin , the standard form is :
To find the foci use the equation: a>b To find the foci use the equation EXAMPLE 1 Sketch the ellipse (This is an ellipse because the coefficient of are different) Divide each term by 9 to get 1 on the right : The vertices on the major axis are (0,3/2) and (0,-3/2) . The vertices on the minor axis are (1,0) and (-1,0). The foci are on the major axis So the foci are (0,1.12) and (0,-1.12) EXAMPLE 2 Determine the equation of the ellipse given the vertices (0,2) and (0,-2) on the minor axis and focus=(3,0) with the center at the origin. EXAMPLE 3 Graph the following ellipse

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