Question

Найти tg a, если 6cos^2a+sina-5=0 и -п/2

Answer 1

6cos²a+sina-5=0
6-6sin²a+sina-5=0
sina=a
6a²-a-1=0
D=1+24=25
a1=(1-5)/12=-1/3⇒sina=-1/3⇒cosa=√(1-sin²a)=√(1-1/9)=√(8/9)=2√2/3
tga=sina/cosa=-1/3:2√2/3=-1/3*3/2√2=-1/2√2=-√2/4
a2=(1+5)/12=1/2⇒sina=1/2 не удов усл