Question

упростите выражение:

Answer 1

tga :(1-tg²a)=sina/cosa : (1-sin²a/cos²a)=sina/cosa * cos²a/(cos²a-sin²a)=
=sinacosa/cos2a=sin2a/2cos2a
ctga:(1-ctg²a)=cosa/sina :(1-cos²a/sin²a)=cosa/sina*sin²a/(sin²a-cos²a)=
=cosasina/(-cos2a)=-sin2a/2cos2a
sin2a/2cos2a -sin2a/2cos2a=0