# Example 3.2
MKS(N, deg)
q = 30 deg
w1 = 2.452 kN
BEGIN
   td = 1 kN
   tb = 1 kN
   td_vec = [-td, 0]
   w1_vec = [0, -w1]
   tb_vec = tb * [cos(q), sin(q)]
   sumf = td_vec + tb_vec + w1_vec
   eqx = sumf[1]
   eqy = sumf[2]
END
solve(eqx, eqy, td, tb)

# Example 3.3
FPS(deg)
q1 = 30 deg
q2 = 45 deg
w = 20 lbf
BEGIN
   tec = 1 lbf
   teg = 1 lbf
   fx = teg * sin(q1) - tec * cos(q2)
   fy = teg * cos(q1) - tec * sin(q2) - w 
END
solve(fx,fy,teg,tec)
BEGIN
   tcd = 1 lbf
   wb = 1 lbf
   fx = tec * cos(q2) - (4/5) * tcd
   fy = (3/5) * tcd + tec * sin(q2) - wb
END
solve(fx,fy,tcd, wb)

# Example 3.4
MKS(N,deg)
q = 30 deg
w = 78.5 N
BEGIN
   tac = 1 N
   tab = 1 N
   fx = tab - tac * cos(q)
   fy = tac * sin(q) - w
END
solve(fx,fy,tac,tab)
kab = 300 N / m
sab = tab / kab
lab = 0.4 m + sab
lac = (2 m - lab) / cos(q)

# Example 3.5
FPS(deg)
q = 30 deg
w = 90 lbf
BEGIN
   fb = 1 lbf
   fd = 1 lbf
   fc = 1 lbf
   fx = fd * sin(q) - (4/5) * fc
   fy = -fd * cos(q) + fb
   fz = (3/5) * fc - w
END
solve(fx,fy,fz, fb, fc, fd)
k = 500 lbf / ft
sab = fb / k

# Example 3.6
MKS(N,deg)
rb = [-2, -3, 6] m
ub = rb / mag(rb)
f1 = [0, 400, 0] N
f2 = [0, 0, -800] N
f3 = 700 N * ub
BEGIN
   fx = 1 N
   fy = 1 N
   fz = 1 N
   f = [fx, fy, fz]
   sumf = f1 + f2 + f3 + f
   y1 = sumf[1]
   y2 = sumf[2]
   y3 = sumf[3]
END
solve(y1, y2, y3, fx,fy,fz)
uf = f / mag(f)
alp = acos(uf[1])
bet = acos(uf[2])
gam = acos(uf[3])

# Example 3.7
FPS(deg)
rb = [-3, -4, 8] ft
ub = rb / mag(rb)
rc = [-3, 4, 8] ft
uc = rc / mag(rc)
w = [0, 0, -40 ] lbf
BEGIN
   fb = 1 lbf
   fc = 1 lbf
   fd = 1 lbf
   sumf = fb * ub + fc * uc + [fd, 0, 0] + w
   y1 = sumf[1]
   y2 = sumf[2]
   y3 = sumf[3]

END
solve(y1, y2, y3, fb,fc,fd)

# Example 3.8
MKS(N,deg)
q1 = 120 deg
q2 = 135 deg
q3 = 60 deg
rd = [-1, 2, 2] m
ud = rd / mag(rd)
ub = [1, 0, 0]
rc = [cos(q1), cos(q2), cos(q3)]
uc = rc / mag(rc)
w = [0, 0, -981] N
BEGIN
   fb = 1 N
   fc = 1 N
   fd = 1 N
   sumf = fb * ub + fc * uc + fd * ud + w
   y1 = sumf[1]
   y2 = sumf[2]
   y3 = sumf[3]
END
solve(y1, y2, y3, fb,fc,fd)
k = 1.5 kN /m 
del_s = fb / k

# Homework Problems:

TBD