I(x cosa+y cos B+z cos r )ds =llx dydz+y dzdx+zdxdy=l) =‖h2 dxdy=h x2+y2≤h 故所求积分为 cos a+y cos B+z cos y)ds ∑ Thch 2. 4 = h 故所求积分为   (x cos + y cos + z cos )dS 2 2 2 4 2 1 = h 4 − h . 2 1 4 = − h       = + + = + + 1 1 1 2 2 2 2 2 2 2 ( cos cos cos ) x dydz y dzdx z dxdy z dxdy x  y  z  ds  +  = 2 2 2 2 x y h h dxdy