Because | cosx |

Use the sum-difference product formula sinx1-sinx2 = 2sin ((x1-x2)/2) * cos ((x1+x2)/2).

Therefore, | sinx1-sinx2 | = 2 *| sin ((x1-x2)/2) | *| cos ((x1+x2)/2) |

& lt= 2 * |(x 1-x2)/2 | = | x 1-x2 |