Нужно найти tgt. подскажите как? cost я уже нашла, он равен 0, 8. условие: sint=-0, 6; -pi/ 2< t < 0

tgt =  sint  /  cost  =  -0,6  / 0,8  = -0,75

tgt=sint/cost=-0,6/0,8=-3/4=-0,75

1) sin(π/3 + α) + sin(π/3 - α) = 2 sin (π/3) * cos α = v3 * cos α.

 

2) sin²(π/4 + α) - sin²(π/4 - α) = (sin(π/4 + α) - sin(π/4 - α)) * ( sin(π/4 + α) + sin(π/4 - α)) =

= (sin π/4 * cos α + cos π/4 *sin α - ( sin π/4 * cos α - cos π/4 *sin α)) *

* (sin π/4 * cos α + cos π/4 *sin α + ( sin π/4 * cos α - cos π/4 *sin α)) =

  = ((v2 / 2) * (cos α + sin α) - (v2 / 2) * (cos α - sin α)) *

* ((v2 / 2) * (cos α + sin α)+ (v2 / 2) * (cos α - sin α)) =

  = (v2 / 2) * (cos α + sin α - cos α + sin α) * (v2 / 2) * (cos α + sin α + cos α - sin α) =

  = 1 / 2 * 2 sin α * cos α = sin α * cos α.

 

3) cos(π/4 - β) - cos(π/4 +  β) = 2 cos (π/4) * cos β = v2 cos β.

 

4) cos²(α - π/4) - cos²(α + π/4) - аналогично п. 2.

1) -15x-9> 3+5x     -15x-5x> 3+9     -20x> 12       x< -12/20       x< - 0.6 -0.6 \\\\\\\\\\ x∈(-∞; -0.6) 2) 16x+8≥1+4x       16x-4x≥1-8       12x≥ -7         x≥ -7/12 -7/12                         \\\\\\\\\\\\\\\\\\\ x∈[-7/12; +∞) 3) 6x+70+50x≥-9x+5     56x+9x≥5-70     65x≥ -65     x≥ -1 -1                   \\\\\\\\\\\\\\\\\  x∈[-1; +∞) 4) x²-6x-16≥0     x²-6x-16=0     d=36+64=100     x₁=(6-10)/2= -2     x₂=(6+10)/2=8     +                 -                 + -2 8 \\\\\\\\\                         \\\\\\\\\\\\\ x∈(-∞; -2]u[8; +∞)