Question

$4cos^{2}x$-5sinxcosx+$sin^{2}x$=0

Answer 1

Разделим на cos²x≠0
tg²x-5tgx+4=0
tgx=a
a²-5a+4=0
a1+a2=5 U a1*a2=4
a1=1⇒tgx=1⇒x=π/4+πn
a2=4⇒tgx=4⇒x=arctg4+πn