= sin(75°) - sin(15°)
= sin(45° + 30°) - sin(15°)
= sin(45°)cos(30°) + cos(45°)sin(30°) - sin(15°)
= (sqrt(2)/2 sqrt(3)/2) + (sqrt(2)/2 1/2) - (1/2)
= (sqrt(6) + sqrt(2)) / 4 - 1/2
= (sqrt(6) + sqrt(2) - 2) / 4