sin²x+sinxcosx=6/5
5sin²x+5sinxcosx=6
5sin²x+5sinxcosx=6(sin²x+cos²x)
sin²x-5sinxcosx+6cos²x=0 两边除以cos²x
tan²x-5tanx+6=0
(tanx-2)(tanx-3)=0
tanx=2tanx=3