# What is the distance between (–5, –1, 1)  and (4, –4, –2)?

Distance =$\sqrt{99}$=$\cong 9.95 .$
WE use the Distance Formula : The distance $d$ between two points $\left(a , b , c\right)$ and $\left(p , q . r\right)$ is $d = \sqrt{{\left(a - p\right)}^{2} + {\left(b - q\right)}^{2} + {\left(c - r\right)}^{2}} .$
In our case, $d = \sqrt{{\left(- 5 - 4\right)}^{2} + {\left(- 1 + 4\right)}^{2} + {\left(1 + 2\right)}^{2}} = \sqrt{81 + 9 + 9} = \sqrt{99} \cong 9.95 .$