# Applied Trigonometry Problem

• Jan 5th 2010, 06:18 AM
clayson
Applied Trigonometry Problem

Having a problem interpreting this question

two forces act at a single point; force one is 20N at an angle of 15 degrees to the horizontal: force two is 30N at an angle of 40 degrees from the horizontal. Determine the magnitude and direction of the resultant of these two forces.

should i take 15 degrees to the horizontal as 165 degrees because it is acting toward the horizontal?, i have to provide a graphical and analytical solution to the problem.

Thanks.

• Jan 5th 2010, 06:26 AM
Ven
Ok heres a picture of the problem.

http://img695.imageshack.us/img695/7528/forces.jpg
• Jan 5th 2010, 09:21 AM
Calculus26
There are 2 ways to approach this problem

1. Using x and y components

Fx = 20cos(15) - 30 cos(40) = -3.66

Fy = -20sin(15) - 30sin(40) = -24.46

F =sqrt(Fx^2 +Fy^2) = 25N

theta= arctan(Fy/Fx) = 81.5 deg meaured from neg x-axis --see attachment

2. Using Laws of Cosines and Sines

See attachment
• Jan 5th 2010, 11:24 AM
earboth
Quote:

Originally Posted by clayson
Having a problem interpreting this question

two forces act at a single point; force one is 20N at an angle of 15 degrees to the horizontal: force two is 30N at an angle of 40 degrees from the horizontal. Determine the magnitude and direction of the resultant of these two forces.

should i take 15 degrees to the horizontal as 165 degrees because it is acting toward the horizontal?, i have to provide a graphical and analytical solution to the problem.

Thanks.

Why not like this?
• Jan 5th 2010, 11:28 AM
Calculus26
Consider the direction of the forces given in the picture in the original problem.

Otherwise I'd agree with you.