Given
[tex]u=15i-8j[/tex]
Find
Magnitude and direction of -3u.
Explanation
given
u = 15i-8j
we have to find magnitude and direction of -3u.
so we multiply both sides by -3
-3u = -3(15i-8j) = -45i+24j
magnitude =
[tex]\begin{gathered} magnitude=\sqrt{45^2+24^2} \\ magnitude=\sqrt{2025+576} \\ magnitude=\sqrt{2601}=51 \end{gathered}[/tex]
[tex]\begin{gathered} \sin\theta_1=\frac{24}{51} \\ \theta_1=\sin^{-1}(\frac{24}{51})=28\degree \\ so, \\ \theta=180\degree-28\degree=152\degree \end{gathered}[/tex]
Final Answer
Therefore , the correct option is 51; 152 degree that is option 4.
