1) 1/cos^2(a) – tg^2(a)-sin^2(a) 2) cos^2(a)+ctg^2(a)-1/sin^2(a) - вопрос №12501421122222212312 от volk910 05.12.2020 10:57

Question

Алгебра: 1) 1/cos^2(a) – tg^2(a)-sin^2(a) 2) cos^2(a)+ctg^2(a)-1/sin^2(a) 3) 1/cos^2(a) – tg^2(a)(cos^2(a)+1) 4) (1+sin^2(a))ctg^2(a) – 1/sin^2(a) 5)sin(a)/(1+cos(a)) + sin(a)/(1-cos(a)) 6)cos(a)/(1+sin(a))+ cos(a)/(1-sin(a))

volk910 · Answer

1)1/cos^2(a) – tg^2(a)-sin^2(a)= 1/cos^2(a) – sin^2(a)/cos^2(a))-sin^2(a)==[1 – sin^2(a) ]/cos^2(a))-sin^2(a)=cos^2(a)/cos^2(a))-sin^2(a)==1-sin^2(a)=cos^2(a)2)cos^2(a)+ctg^2(a)-1/sin^2(a)=cos^2(a)+[cos^2(a)-1]/sin^2(a)==cos^2(a)-sin^2(a)]/sin^2(a)=cos^2(a)-1 = -sin^2(a)3)1/cos^2(a) – tg^2(a)(cos^2(a)+1)=1/cos^2(a) – sin^2(a)-sin^2(a)/(cos^2(a)==(1 – sin^2(a))/cos^2(a)-sin^2(a)=1-sin^2(a)=cos^2(a)4) (1+sin^2(a))ctg^2(a) – 1/sin^2(a)=cos^2/sin^2 +cos^2 – 1/sin^2(a)==(cos^2 - 1)/sin^2 +cos^2= -sin^2/sin^2...