(1)已知:(4sinx-2cosx)/(5cosx+3sinx)=6/11 求sinx乘以cosx的值
问题描述:
(1)已知:(4sinx-2cosx)/(5cosx+3sinx)=6/11 求sinx乘以cosx的值
(2)证明(cosx/1+sinx) - (sinx/1+cosx)=2(cosx-sinx)/1+sinx+cosx
(3)求证:sin²x乘以tanx + cos²x乘以cotx+2sinx乘以cosx=tanx+cotx
要用 sin²X+cos²X=1
和tanx=sinx/cosx来做
答
1.(4sinx-2cosx)除以cosx/(5cosx+3sinx)除以cosx=6/11
(4tanx-2)/(5+3tanx)=6/11
令tanx=p
则4p-2/5+3p=6/11
11*(4p-2)=6*(5+3p)
26p=52
p=2