You are given a vector in the xy plane that has a magnitude of 84.0 units and a y component of -49.0 units.

Assuming the x component is known to be positive, specify the vector V which, if you add it to the original one, would give a resultant vector that is 71.0 units long and points entirely in the - x direction.

I already solved that the x component is 68.2

4 answers

Assuming the x component is 68, then

V+68x-49y= -71x

which means V= -71x-68x+49y
fail...
34.4
Vo = 84[Ao]. = Initial vector.
Y = 84*sin A.
-49 = 84*sin A,
A = -35.7o = 35.7o S. of E.

Vo = 84[-35.7o].

X = 84*Cos(-35.7) = 68.
Y = -49(given).

68 - 49i + V = -71.
V = -71-68 + 49i = -139 + 49i = 147.4[-19.42o] = 147.4[19.42] N. of W.