Rút gọn : (1+ cosa – sina) / (1- cosa – sina ) 30/09/2021 Bởi Adeline Rút gọn : (1+ cosa – sina) / (1- cosa – sina )
= [1-2sina/2cosa/2+(2cos^2a/2 – 1)]/[1-2sina/2cosa/2-1+2sin^a] =2cosa/2(cosa/2-sina/2)/[2sina/2(sina/2-cosa/2)] = -cota/2 Bình luận
= [1-2sina/2cosa/2+(2cos^2a/2 – 1)]/[1-2sina/2cosa/2-1+2sin^a]
=2cosa/2(cosa/2-sina/2)/[2sina/2(sina/2-cosa/2)]
= -cota/2