If cos (x + π 4) = 45, X ∈ (− π 4, 0), then SiNx=______ .

If cos (x + π 4) = 45, X ∈ (− π 4, 0), then SiNx=______ .

∵ x ∈ (− π 4, 0) ∵ 0 < x + π 4 < π 4 ∵ sin (x + π 4) = 1 − 1625 = 35 ∵ SiNx = sin (x + π 4 - π 4) = sin (x + π 4) cos π 4-cos (x + π 4) sin π 4 = - 210, so the answer is: - 210