Question

1) Дано: ctga = 2 a∈(π:2π) Найти: sin a
2)Вычислите: sin a, tg a, ctg a, если cosa = 40/41, 3π/2<a<2π

Answer 1

1
sin²a=1:(1+ctg²a)=1:(1+4)=1/5
sina=-√5/5
2
cosa=40/41
sina=-√(1-cos²a)=-√(1-1600/1681)=-√(81/1681)=-9/41
tga=sina/cosa=-9/41:40/41=-9/41*41/40=-9/40
ctga=1/tga=1:(-9/40)=-40/9