Question

упростить 1+tg a tg b/ 1-tg a tg b )))))

Answer 1

(1+sin(a)*sin(b)/(cos(a)*cos(b)))/(1-sin(a)*sin(b)/(cos(a)*cos(b))) = (cos(a)*cos(b)+sin(a)*sin(b))/(cos(a)*cos(b)-sin(a)*sin(b)) = cos(a-b)/cos(a+b).