Question

найдите sin и ctg,при cosa=0.8 и 0<a<п/2

Answer 1

sin2a = 1 - cos2a

sin2a = 1 - (0.8)2

sina= 0.6

ctg= cos/sin

ctg= 1.3

 

Answer 2

$sinx=sqrt{1-0.64}=0.6$$ctg=frac{cosx}{sinx}=frac{0,8}{0.6}=1frac{1}{3}$