在选修4-4学习了直线与圆的极坐标方程,同学们做题时经常习惯把极坐标方程转化成直角坐标方程,这种方法体现了化归的数学思想,它的缺点是运算量较大.实际上,极坐标中的极径ρ、极角θ都有明显的几何意义,如果我们能根据题意,画出图形,就能数形结合,快速解题.下面我们通过例题来体会“数形结合”的神奇. In elective 4-4 learning the polar and circular polar equations, students are often used to do when the polar coordinate equations into Cartesian equations, this method reflects the return of the mathematical thinking, its disadvantage is that the computational complexity In fact, polar coordinates in the polar radius ρ, polar angle θ have obvious geometric significance, if we can according to the inscription, drawing graphics, we can combine the number of forms, fast problem solving. Below we experience through examples “Combination of numbers ” magic.