10sin²x-6sinxcosx-8sin²x-8cos²x=0
2sin²x-6sinxcosx-8cos²x=0/2cos²x≠0
tg²x-3tgx-4=0
tgx=a
a²-3a-4=0
a1+a2=3 U a1*a2=-4
a1=-1⇒tgx=-1⇒x=-π/4+πn
a2=4⇒tgx=4⇒x=arctg4+πn
10sinx/2cosx/2=3sin²x/2+3cos²x/2-2cos²x/2+2sin²x/2=0
5sin²x/2-10sinx/2cosx/2+cos²x/2=0/cos²x/2
5tg²x/2-10tgx/2+1=0
tgx/2=a
5a²-10a+1=0
D=100-20=80
a1=(10-4√5)/10=1-0,4√5⇒tgx/2=1-0,4√5⇒x/2=arctg(1-0,4√5)+πn⇒
x=2arctg(1-0,4√5)+2πn,n∈z
a2=1+0,4√5⇒tgx/2=1+0,4√5⇒x/2=arctg(1+0,4√5)+πn⇒
x=2arctg(1+0,4√5)+2πn,n∈z
A7? далее просто подставляй цифры.