Solution
For this case we have the following number:
u= 35i -12j
And we want to find the magnitude and direction of -3u so we have this:
-3 u = -105i + 36j
Then the magnitude is given by.
[tex]M=\sqrt[]{(-105)^2+(36)^2}=111[/tex]
And the angle can be founded using this:
[tex]\theta=\tan ^{-1}(\frac{36}{-105})=-18.92[/tex]
Therefore the angle is:
-18.92 + 360 º= 341º
The answer is:
111, 341º
