20 0 3年高考数学选择填空题大多数都是常规基础题 ,许多题都要通过运算才能找到问题答案 ,因而花费了许多时间 ,造成计算繁杂的恐惧心理 .现对其中的部分试题进行剖析与反思 ,寻找突破口 ,希望能对训练数学运算思维有着借鉴作用 .1.已知x∈ - π2 ,0 ,cosx =45,则tan2x =(　　 In the 2030 college entrance examination mathematics, most of the blank-filling questions were routinely based questions. Many of the questions had to be solved by operations to find the answers to the questions. Therefore, it took a lot of time and caused complicated calculations of fear. Now some of these questions are analyzed and analyzed. Rethinking, looking for breakthroughs, hoping to learn from mathematics thinking. 1. Known x∈ - π2, 0, cosx = 45, then tan2x = (