有些数学题由于给出的条件较多或者较隐蔽。在解题时,往往造我一种思路混乱、条理不清的感觉,容易陷入数与式的迷途。若借助图形来要,则可化繁为简,化难为易,准确,迅速地求出结果。例如,八四年高考题(理工农医类)中的第一题5小题: 如果θ是第二象限角,且满足cos(θ/2)-sin(θ/2)=(1-sinθ)~1/2,那么θ/2 (A)是第一 Some math problems are given more or more hidden conditions. In solving problems, I often create a sense of confusion and unclear thinking, and I easily fall into the lost way of numbers and styles. If you rely on graphics, you can simplify everything, make it easy, and accurately and quickly determine the results. For example, the first question in the eighty-fourth college entrance examination question (academics, agronomy, medicine) is as follows: If θ is a second quadrant angle and satisfies cos(θ/2)-sin(θ/2)=(1-sinθ )~1/2, then θ/2 (A) is the first