tanA+cotA=3,A是锐角,求tan^A+cot^A=?
问题描述:
tanA+cotA=3,A是锐角,求tan^A+cot^A=?
答
锐角,tanA>0
(tanA+1/tanA)^2=3*3=9
tan^A+1/tan^A+2=9
tan^A+cot^A=tan^A+1/tan^A=7