I confused about how to tell what shape something will be by its formula.
for example..
I know that x^2+y^2=1 is a circle
and
sqrt(x^2+y^2)=1 is a semicircle
but how do you know what a shape like
exp{-x^2-y^2) would be..?
Also are there other types of formulas which include the circle formula, that are common as integration problems?