Chapter 9.5, Problem 9E

To determine

Tofind:Distance between points C and D.

Answer to Problem 9E

  $d=\sqrt{10}$

Explanation of Solution

Given information:

  $\begin{array}{l}C=\left(1,2\right)=\left(x_1,y_1\right)\\ D=\left(2,-1\right)=\left(x_2,y_2\right)\end{array}$

Concept Used:

Distance between two points - $d=\sqrt{{\left(x_2-x_1\right)}^2+{\left(y_2-y_1\right)}^2}$

Calculation:

  $\begin{array}{l}d=\sqrt{{\left(x_2-x_1\right)}^2+{\left(y_2-y_1\right)}^2}\\ \Rightarrow d=\sqrt{{\left(2-1\right)}^2+{\left(-1-2\right)}^2}\\ \Rightarrow d=\sqrt{{\left(1\right)}^2+{\left(-3\right)}^2}\\ \Rightarrow d=\sqrt{1+9}\\ \Rightarrow d=\sqrt{10}\end{array}$