求极限:lim tan2x·tan(π/4-x)(x趋于π/4)
问题描述:
求极限:lim tan2x·tan(π/4-x)(x趋于π/4)
越详细越好,最好有每一步的步骤
答
lim(x→π/4) tan2x*tan(π/4-x)
=lim(x→π/4) 2tanx/(1-tan^2x)*[tan(π/4)-tan(x)]/[1+tan(π/4)*tan(x)]
=lim(x→π/4) 2tanx/(1-tan^2x)*[1-tan(x)]/[1+tan(x)]
=lim(x→π/4) 2tanx/(1+tanx)^2
=2tanπ/4/(1+tanπ/4)^2
=2/(1+1)^2
=2/4
=1/2是用极限的知识点解答吗这里面大部分考到了三角公式的变换
极限的考点基本上没有
就最后趋于的时候的代入不客气