If cos a = 15/17, then sin a = sqrt(1 - (cos a)^2) = sqrt(1 - (225/289)) = sqrt(64/289) = 8/17.
Therefore, sin 34a = sin(34 * arcsin(8/17)) = sin(arcsin(8/17)) = 8/17.
If cos a = 15/17, then sin a = sqrt(1 - (cos a)^2) = sqrt(1 - (225/289)) = sqrt(64/289) = 8/17.
Therefore, sin 34a = sin(34 * arcsin(8/17)) = sin(arcsin(8/17)) = 8/17.