how to plot these functions?

how to plot these functions in matlab 2013b?

1. 49y^2-56x+16=0
2. X^2+Y^2-(32/49)=0

[dpb]

 doc meshgrid % example of writing 2D function and plotting

Answer 1

[Walter Roberson]

See the Example at http://www.mathworks.com/help/matlab/ref/ndgrid.html

Answer 2

[Roger Stafford]

Successfully plotting such relationships often involves selecting the appropriate parameter. In the case of the first equation, that would be one of the variables, namely, y. If a range of y values is generated using 'linspace', then x is easily expressed as a function of y:

 y = linspace(-5,5,1000);
 x = (49*y.^2+16)/56;

This can then be plotted:

 plot(x,y)

For the second equation, which is that of a circle, a good parameter to use is the angle of a vector from the origin to a point (X,Y) on the circle, which can be generated to vary between 0 and 2*pi. Then X and Y can be expressed in terms of that angle and the circle plotted.