Question

Решите пожалуйста умоляю 2-3 задания!!

Answer 1

2. $(1-sin alpha*tgalpha*cosalpha)(1+tg^{2} alpha)= (1- frac{sin alpha*sin alpha*cosalpha}{cosalpha} )(1+ tg^{2} alpha )=$$=(1- sin^{2} alpha)(1+ tg^{2} alpha )= cos^{2} alpha *(1+ tg^{2} alpha )=cos^{2} alpha * frac{1}{cos^{2} alpha}=1$

3.$cos frac{7 pi }{3}-sin frac{11 pi }{6} =0,5-(-0,5)=1$