Question 297579
Here's a graph of a circle.


{{{graph(600,600,-10,10,-10,10,sqrt(36-x^2),-sqrt(36-x^2))}}}


Here's a graph of the same circle.


{{{graph(600,600,-10,10,-20,20,sqrt(36-x^2),-sqrt(36-x^2))}}}


In the first graph it looks like a circle.


In the second graph it looks like an ellipse.


All I did was change the scale of the vertical axis (the y-axis).


In the first graph the x and y axis spanned from -10 to 10.


In the second graph, the x axis spanned from -10 to 10 and the y axis spanned from -20 to 20.


If you are not aware of the scaling of each axis, you can definitely be misled by what's on the graph.