Why do you need to know that a circle has 360 degrees when creating a circle graph

If 2(a^2+b^2)=(a+b)^2 then, > a+b=0, > ab=0, > a=b, > 2a=b

This is a map of the mars exploration rover opportunity predicted landing site on mars. the scale is 1cm : 9.4km. what are the approximate measures of the actual length and width of the ellipse? i mostly need to know how to set it up : )

How many solutions does the nonlinear system of equations graphed below have? a. one b. zero c. four d. two