Question

Упростите выражения : (tg a+ctg a)(1+ cos a)(1-cos a) 

Answer 1

$(frac{sin alpha }{cos alpha }+ frac{cos alpha }{sin alpha })(1-cos ^{2} alpha ) = frac{sin ^{2} alpha +cos ^{2} alpha }{cos alpha cdot sin alpha }cdot sin ^{2} alpha = frac{sin alpha }{cos alpha } =tg alpha$