Question

求tanα，以及tan(a-5π/4)

已知0<ɑ<π/2，(sin2ɑ+sin2ɑ)/(cos2ɑ+cos2ɑ)=33/22，求tanα，以及tan(a-5π/4)
打错字了，以图片为准，谢谢，应该是=33/23

Answer 1

(1) (sin²α+2sinαcosα)/(cos²α+cos²α-sin²α)=33/23
(tan²α+2tanα)/(2-tan²α)=33/23
∴33(2-tan²α)=23(tan²α+2tanα)
即28tan²α+23tanα-33=0
(4tanα-3)(7tanα+11)=0
而0<α<π/2，∴tanα>0，∴tanα=3/4
(2) 原式=tan(α-π/4)=(tanα-tanπ/4)/(1+tanαtanπ/4)
=(3/4-1)/(1+1*3/4)
=-1/7

望采纳

Answer 2

追问

里面啥也没有呀？