Question

Помогите пожалуйста разобраться

Answer 1

$frac{cos(x)cos(y)-cos(x+y)}{cos(x-y)-sin(x)cos(y)}=$

$frac{cos(x)cos(y)-cos(x)cos(y)+sin(x)sin(y)}{cos(x)cos(y)+sin(x)sin(y)-sin(x)cos(y)}=$

$frac{sin(x)sin(y)}{cos(x)cos(y)}=tg(x)tg(y)$