Elastic Glancing Collision-HELP

[psychfan29]

Elastic Glancing Collision-HELP!

A white ball, mass of 1 kg has a speed of 1.68 m/s and a yellow ball, mass of 2kg, is at rest prior to an elastic glancing collision. After the collision the white ball has a speed of 1.24 m/s. To the nearest tenth of a degree, measured counterclockwise from east, what angle does it scatter at if the yellow ball is scattered at 280degrees?

I don't know what equations to use for this problem!

 

[psychfan29]

I used this equation:

1/2mv_1i^2 = 1/2mv_1f^2 + 1/2mv_2f^2 (the 1i, 1f, and 2f are subscripts indicating which velocities)

When I plugged in the numbers from the problem, I got that the final velocity for the yellow ball is 0.801m/s.

I then used the following equation:

Py=1kg(1.24m/s)sintheta+2kg(vyellow)sin280

But sin becomes greater than 1, so it's a domain error.

Am I doing something completely wrong?
Or is it possible that for this problem to work, the mass of the white ball must be greater than that of the yellow ball?