Moderate# Magnitude of a Vector Sum

CLMECH-A3KEWR

Vectors $\vec { C }$ and $\vec { D}$ are perpendicular to each other. The magnitude of vector $\vec { C }$ is 5 and that of vector $\vec { D }$ is 8.

About how much is the magnitude of vector $(2\vec { C } -3\vec { D })$?