Question

Помогите с решением!


$(tg alpha * cos alpha ) ^{2} + (ctg alpha * sin alpha ) ^{2}$

Answer 1

$(tg alpha * cos alpha ) ^{2} + (ctg alpha * sin alpha ) ^{2} =( frac{sin alpha }{cos alpha } * cos alpha ) ^{2} + ( frac{cos alpha }{sin alpha } * sin alpha ) ^{2} =$
$=sin^2 alpha +cos^ 2alpha =1$