sin(x+7π/6)＝sin(x＋π/6＋π)＝－sin(x+π/6)＝－1/4
cos(11π/6-x)＝cos(2π－(x+π/6))＝cos(x+π/6)＝±√15/4
所以,sin(x+7π/6)+cos^2 (11π/6-x)＝－1/4＋15/16＝11/16