一、问题的提出学习了高中数学选修4-4“极坐标与参数方程”之后,年级进行了一次周考,其中的一道填空题如下:过点P(4,3)的直线l_1的参数方程为x=4+6/13~(1/2)t,y=3+4/13~(1/2)t(t为参数),l_1与直线l_2:x+y-2=0的交点为Q,求|PQ|.测试结果是全年级96.8%的答案是13~(1/2)2,正确作答的不到4%.调查走访学生,回 First, the problem raised Learning high school mathematics elective 4-4 “polar coordinates and parametric equation ”, the grade conducted a weekly test, one of the fill in the blank as follows: P (4,3) over a straight line l_1 The parameter equation is: x = 4 + 6/13 ~ (1/2) t, y = 3 + 4/13 ~ (1/2) t The intersection point is Q, seeking | PQ | .The test result is 96.8% of the whole grade, the answer is 13 ~ (1/2) 2, the correct answer is less than 4%