这道题看不懂,为什么相等请写出过程,
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/06/24 10:50:35
这道题看不懂,为什么相等请写出过程,
2sinacosa/(sin^2a+cos^2a)=2tana/(tan^2a+1)
2sinacosa/(sin^2a+cos^2a)=2tana/(tan^2a+1)
![这道题看不懂,为什么相等请写出过程,](/uploads/image/z/12781225-1-5.jpg?t=%E8%BF%99%E9%81%93%E9%A2%98%E7%9C%8B%E4%B8%8D%E6%87%82%2C%E4%B8%BA%E4%BB%80%E4%B9%88%E7%9B%B8%E7%AD%89%E8%AF%B7%E5%86%99%E5%87%BA%E8%BF%87%E7%A8%8B%2C)
2sinacosa/(sin^2a+cos^2a) 分子分母都提出公因式cos^2a
=cos^2a*2sina/cosa / cos^2a (sin^2a/cos^2a +1)
=2tana/(tan^2a+1)
=cos^2a*2sina/cosa / cos^2a (sin^2a/cos^2a +1)
=2tana/(tan^2a+1)