Question

4√5 * sin a/2 -?
Если sin a = -0.8
pi

Answer 1

cosa=-√(1-sin²a)=-√(1-0,64)=-√0,36=-0,6
sin²(a/2)=(1-cosa)/2=(1+0,6)/2=1,6/2=0,8
sin(a/2)=2/√5
4√5*sin(a/2)=4√5*2/√5=8

Answer 2

$cosa = - \sqrt{} (1 {sin}^{2} a) = - \sqrt{} (1 - 0 \: 64) = - \sqrt{} 0 \: 36 = - 0 \: 6$
${sin}^{2} (a$/
$2) = (1 \: cosa)$/$2 = (1 + 0 \: 6$tex]2 = 1 \: 6[/tex]/$2 =0 \: 8$
$sin(a |2) = 2 | \sqrt{5} [tex][tex]4 \sqrt{5} \times sin(a |2) = 4 \sqrt{5} = 8$