⑩天掌 Teaching Plan on Advanced Mathematics o dz 0 1,-2,1) d 由此得切向量T={1,0,-1}, 所求切线方程为 x-1y+2z-1 法平面方程为(x-1)+0.(y+2)-(z-1)=0, →x-z=0 tianjin polytechnic dmivendityTianjin Polytechnic University Teaching Plan on Advanced Mathematics T = {1, 0,−1},  所求切线方程为 , 1 1 0 2 1 1 − − = + = x − y z 法平面方程为 (x − 1) + 0 ( y + 2) − (z − 1) = 0,  x − z = 0 0, (1, 2, 1) = dx − dy  1, (1, 2, 1) = − dx − dz 由此得切向量