Question

Спростіть вираз sin(-x) + cos(-x)tg(-x)

Answer 1

sin(-x) + cos(-x)tg(-x) =  -sin(x) + cos(x) * ( - tg(x)) = -sin(x) + cos(x) * $(- frac{sin(x)}{cos(x)} )$ =  -sin(x) * (-sin(x)) = sin²(x)