Distance Between Two Points

The distance of a point $\left(3,4\right)$ from the origin is _____ units.

Show that the points $\left(-4, -7\right), \left(-1, 2\right), \left(8, 5\right) \mathrm{and} \left(5, -4\right)$ taken in order are the vertices of a Rhombus.

If the distance between two points $\left(x,1\right)$ and $\left(-1,5\right)$ is $5$. Find the value of $x$

If $\mathrm{A} \left(4, 0\right) \mathrm{and} \mathrm{B} \left(0, \mathrm{y}\right)$ and $\mathrm{AB}=5$, find the possible values of $y$.