Sin²x+3cosxsinx+1=0
2sin²x+3cosxsinx+cos²x=0 /cos²x≠0
2tg²x+3tgx+1=0
tgx=a
2a²+3a+1=0
D=9-8=1
a1=(-3-1)/4=-1⇒tgx=-1⇒x=-π/4+πn
a2=(-3+1)/4=-1/2⇒tgx=-1/2⇒x=-arctg0,5+πn
(cos-sin) (cos+sin)
-------------------------- = cos-sin
(cos+sin)
У=4х+5 у=21
21=4х +5
4х=21-5
х= 16/4
х=4
1. 50 + 3 * ( 2x - 1 ) = 71
50 + 6x - 3 = 71
6x = 71 - 50 + 3
6x = 24
x = 4
<span>V=24-1,2t
1.2t=24-V
t=10*(24-V)/12</span>