## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$\sqrt{43}\approx 6.56$
The formula to calculate a distance $d$ from $P_1(x_1,y_1,z_1)$ to $P_2(x_2,y_2,z_2)$ is written as: $d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2}$ Substitute the given values in the above formula to obtain: $d=\sqrt{(4-1)^2+(-2-3)^2+(1-(-2))^2}\\=\sqrt {(3)^2+(-5)^2+(-3)^2}\\=\sqrt{9+25+9}\\ =\sqrt{43}$