Question

If L and M are the feet of perpendiculars from P (3, 4, 5) on xy and yz-planes, then LM =____________________________.

Answer 1

For given point P(3, 4, 5)
Let L and M be the feet of perpendiculars from P to xy and yz-planes respectively
∴ L is given by (3, 4, 0) and M is given by (0, 4, 5)

$\begin{array}{rcl}\therefore LM& =& \sqrt{{\left(3-0\right)}^2+{\left(4-4\right)}^2+{\left(0-5\right)}^2}\\ & =& \sqrt{9+0+25}\\ \mathrm{i}.\mathrm{e}LM& =& \sqrt{34}\end{array}$