来源:学生作业帮 编辑:大师作文网作业帮 分类:数学作业 时间:2024/11/18 10:08:15
求积分,1/1+(cosx的二次方)dx.
∫1/1+(cos^2x)dx
=∫(sin^2x+cos^2x)/(sin^2x+cos^2x+cos^2x)dx
=∫(sin^2x+cos^2x)/(sin^2x+2cos^2x)dx (被积函数上下同除以cos^2x)
=∫(tan^2x+1)/(tan^2x+2)dx
=∫(sec^2x)/(tan^2x+2)dx
= ∫1/(tan^2x+2)dtanx
=1/√2*arctan(tanx/√2)+C