Question

(tga-ctga)^2-(tga+ctga)^2

Answer 1

(tga-ctga)²-(tga+ctga)²=tg²a-2tgactga+ctg²a-(tg²a+2tgactga+ctg²a)=

=tg²a-2tgactga+ctg²a-tg²a-2tgactga-ctg²a=-4tgactga=-4

(tgactga=sina/cosa×cosa/sina=1)

ili

(tga-ctga+tga+ctga)(tga-ctga-tga-ctga)=2tga.(-2ctga)=-4tgactga=-4

(A²-B²=(A+B)(A-B), A=tga-ctga, B=tga+ctga)