How Do They Calculate the 9 Degrees in the Force Diagram?

[circuscircus]

Homework Statement

http://img61.imageshack.us/img61/4585/8m1cdhx1.gif

I understood every except, How do they get the 9 degrees in part c?

Homework Equations

The Attempt at a Solution

 

[Doc Al]

Look at the components of the resultant of the three forces: using an inverse tangent you should be able to find the angle it makes with the x axis. (Draw a right triangle.)

 

[circuscircus]

So then is arctan(30/190) 9 degrees?

(I don't have access to a radian calculator right now), also how do they get the 19N?

 

[Doc Al]

So then is arctan(30/190) 9 degrees?

Yes.

(I don't have access to a radian calculator right now), also how do they get the 19N?

You don't need a radian calculator. (If ever you don't have a calculator handy, Google has one.)

The 19 N makes no sense. But the components are close enough, so you should be able to figure the magnitude properly from that.

 

[circuscircus]

So the real F is sqrt(130^2+30^2) am I correct?

 

[Doc Al]

So the real F is sqrt(130^2+30^2) am I correct?

Where did the 130 come from?