if a satellites position is vecotr function, r$($t$)$ and $||$r$($t$)$ is constant for all values if t$.$ which of these are true? a$.$ r$($t$)$r$($t$)=1$ b$.$ r$($t$)$a$($t$)=0$ c$.$ v$($t$)$a$($t$)=0$