Решие
<span>sin α/2 =2/√7 , 0<α<п
sin</span>²(α/2) = (1 - cosα)/2
(2/√7)² = (1 - cosα)/2
1 - cosα = 8/7
cosα = 1 - 8/7
cosα = - 1/7
sinα = √(1 - cos²α) = √(1 - (- 1/7)²) = √(1 - 1/49) = √(48/49) =
= 4√3 / 7
9.4x -23.5 =7.2 -0.6x -6.5
9.4x +0.6x =23.5 +0.7
10x =24.2
x =24.2/10
x =2.42
Решение
cos^2альфа+tg^2альфаctg^2альфа+sin^2альфа =
<span>= cos^2альфа + 1 + sin^2альфа = 1 + 1 = 2</span>
15Х-30-6Х-12=24Х-18
9Х-42-24Х+18=0
-15Х-24=0
<span>Х=-1,6
</span>