?

Multivariable Calculus

Free Version

Upgrade subject to access all content

Moderate

Angles with Coordinate Axes

MVCALC-IO4K5T

For each vector in this question, let $\alpha$, $\beta$, and $\gamma$ denote the angle that the vector makes with the unit vector ${\bf i}$, ${\bf j}$, and ${\bf k}$, respectively.

For which one of the five vectors is it true that $\cos \alpha +\cos \beta =\cos \gamma $?

A

$\langle 2,0,1 \rangle$

B

$\langle 1,5,3 \rangle$

C

$\langle 3,7,4 \rangle$

D

$\langle 12,7,5 \rangle $

E

$\langle 3,2,5 \rangle$