I was investigating the graphs of equations of the form $x^k+y^k=r^k$. I am not sure how to ask this so I will try to simplify the problem first.
For simplicity sake lets let $r=2$, now
For $k=1$, I get a line.
$x+y=2$.
For $k=2$, I get a circle with radius 2.
$x^2 + y^2= 4$.
Is there a name for the image I get when k=3?
$x^3+y^3=8$?
Are there more names of the geometric figures for higher powers of $k \in N$?
I have included a picture of these two cases where $k=3$ and $k=4$
