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A force of 240 Newtons acts at 30 degrees. Another force of 500 Newton acts at the same point at 240 degrees. Find the resultant vector and its magnitude and angle. I got the magnitude using the pythagorean theorem. Now I don't know the degree.

Dylan
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1 Answers1

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Find new vector:

$240cos(30)+500cos(240)=-42.1539$

$240sin(30)+500cos(240)=-313.0127$

Now use $tan$ to find the degree. $arctan\frac{-313.0127}{-42.1539}$$=82$

So the angle is $82$ so $180+82=262$ since it lies in the third quadrant

  • This seems to have an error or two. – Ted Shifrin Oct 04 '19 at 00:18
  • The thing I don't understand is, the third quadrant means the angle measure is between 180 and 270. How do I know if I subtract 82 from 270 OR if I add it to 180? – Dylan Oct 04 '19 at 01:17
  • Its because when you calculated $tanx$ to find the degree, you assumed $x$ was adjacent and $y$ was opposite leg of the triangle. So you have to use the $x$-axis not the $y$ axis as a reference – Sina Babaei Zadeh Oct 04 '19 at 02:37