Posted by Matt on Wednesday, January 20, 2010 at 7:44pm.
Vector V1 is 6.4 units long and points along the negative x axis. Vector V2 is 8.9 units long and points at 60 degrees to the positive x axis
1) find x and y components of v1 and v2?
2) find magnitude of the sum v1+v2?
3) find the angle of the sum v1+v2?
I found the answers to part 1 (v1= 6.4,0 and v2= 4.5,7.7) and part 2 (8.0) but need help with part 3. thanks!

physics  Damon, Wednesday, January 20, 2010 at 8:02pm
I assume 60 degrees in the +y direction
V1x = 6.4
V1y = 0
V2x = 8.9 cos 60 = 4.45 agree
V2y = 8.9 sin 60 = 7.71 agree
Vx= 6.4 + 4.45 = 1.95
Vy= 0+ 7.71 = 7.71
sqrt(Vx^2+Vy^2) = 7.95 agree
tangent of angle above x axis = 7.71/1.95
= 3.954
so that angle = 75.8 degrees above x axis
which is
180  75.8 = 104.2 degrees counterclockwise from +x axis
ALWAYS sketch a graph !!!!