Question

а)Tga*ctga-(sin^2a-1)/(1-cos^2a)
б)(1-cos^2a)/(1-sin^2a)+ctga*tga
в)(2sin(a-B)+sin(B-a))/(2cos(a-B)-co

Answer 1

а) =1-(-cos^2a)/sin^2a= 1-(-ctg^2a)=1+ctg^2a
б) = sin^2a/cos^2a+1=tg^2a+1