MHB Hcc8.12 Find the sum of vectors

[karush]

$\tiny{hcc8.12}$
$\textsf{Find the sum of vectors $(10, \, 45^o)$ and $(7, \, 150^o)$}\\$$\begin{align*}\displaystyle
\textsf{magnitude}
&=\sqrt{(10\cos45^o - 7\cos150^o)^2 + (10\sin45^o - 7\sin150^o)^2} \approx 12.114
\end{align*}$

ok an online vector sum calculator returned 10.619

so wheres my error?

 

[lfdahl]

Hi, karushYou have calculated the magnitude of the difference of the two vectors.

If you add the coordinates, I´m sure, you´ll get the online answer.

 

[karush]

Hi, karushYou have calculated the magnitude of the difference of the two vectors.

If you add the coordinates, I´m sure, you´ll get the online answer.

$$10.6191$$ is the online calculated magnitude which I could not derive

 

[lfdahl]

$$10.6191$$ is the online calculated magnitude which I could not derive

Try to calculate the magnitude with the coordinate values:

$(10\cos 45^{\circ}+7\cos 150^{\circ})$ and $(10\sin 45^{\circ}+7\sin 150^{\circ})$

 

[karush]

Try to calculate the magnitude with the coordinate values:

$(10\cos 45^{\circ}+7\cos 150^{\circ})$ and $(10\sin 45^{\circ}+7\sin 150^{\circ})$

that returns $3.71084$ which isn't it

 

[skeeter]

$R_x=5\sqrt{2}-\dfrac{7\sqrt{3}}{2}$

$R_y=5\sqrt{2}+\dfrac{7}{2}$

$|R|= \sqrt{R_x^2 + R_y^2} \approx 10.619$

 

[karush]

strange thought that is what I had

mahalo