Can Somebody Explain These Steps for Me(answer given, dont get steps in between)

[imapeiceofwod]

2.45 and 2.55 i don't get the steps, on how they get to the final answers, can someone explain please.

http://ea2.mccormick.northwestern.edu/homework/hw1-sol.pdf

 

[Inferior89]

2.45 The vector sum of the forces is zero. This means that every component of the sum of force vectors is zero, i.e: sum of Fx = 0 and sum of Fy = 0.

Split F1,F2 and F3 into their horizontal and vertical components.

Sum of Fx is the sum of all horizontal components of the forces.
Sum of Fy is the sum of all vertical components of the forces.

Both of these should be zero.

You have two equations and two unknowns. Solve for these unknowns.