Thread: 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.

Ok heres a picture of the problem.

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

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?

Consider the direction of the forces given in the picture in the original problem.

Otherwise I'd agree with you.