(sin56cos79+sin79cos56)/(cos66cos44-sin66sin44)=
=sin(56+79)/cos(66+44)=cos135/cos110=sin45/(-cos20)<0
(sin37+cos37)/(1-cos74+sin74)=(sin37+sin53)/(1-(cos74-cos16))=
=2sin90cos8/(1+2sin90sin24)=(2cos8/(1+2sin24)>0
(sin56cos79+sin79cos56)/(cos66cos44-sin66sin44) <(2cos8/(1+2sin24)
( a - 5 )^2 + 2( 5 - a ) + 1 = a^2 - 10a + 25 + 10 - 2a + 1 = a^2 - 12a + 36
X+y=16 I×9 9x+9y=144 Складываем эти уравнения:
2x/3=3y/5 I×15 10x-9y=0 19x=144 x=144/19 ⇒ y=160/19.
Y = - 5X + B
C ( 10 ; - 52 )
- 52 = - 5 * 10 + B
B = - 52 + 50
B = - 2
Tg105градусов=tg(90+15)=ctg90=0