Verified answer

sinB / b = sinA / a

sinB / 4.21 = sin(3-.4) / 1.43

sinB = 4.21sin(3-.4) / 1.43

B = arcsin(4.21sin(3-.4) / 1.43)

but I cant tell you what it is because i don't know what you mean by 3-.4

if you meant 30.4degrees than no solution exists because 4.21sin(30.4) / 1.43 > 1 and you cant take sin inverse (arcsin) of a number greater than 1 or less than -1

"none"

Your numbers don't make sense. What do you mean by A = 3-.4? Do you mean A = 2.6? Also, are those angles in degrees or radians? If they are in radians, they don't work because the three angles must add up to pi.

Well, if you know A, a, and b, the general method is to do this:

You know c because a+b+c = 180 degrees or pi radians.

By the law of sines, we know sin a/A = sin b/B = sin c/C

Therefore, B = (A*sin b)/(sin a) and C = (A*sin c)/(sin a)

Plug in the values and you're done.