Rectangular and polar

A point can be written in $P(x,\ y)$, with $\displaystyle x$ across and $\displaystyle y$ up, or in $P(r,\ \theta)$, with a distance $\displaystyle r$ and an angle $\displaystyle \theta$. $r=\sqrt{x^{2}+y^{2}}$. Going the other way, $x=r\cos\theta$. The calculator converts both ways and also stores the results in memories $\displaystyle X$ and $\displaystyle Y$.