Question

помогите решить уравнения:

ctg^2x - tg^2x = 8ctg2x

 

sin^4x + cos^4x = cos^2x + 1/4

 

sin (3П/2 - x) + (3x + П/2) = 0

Answer 1

(ctgx+tgx)(ctgx-tgx)=4(ctgx-tgx)

tgx=ctgx

sin^2x-cos^2x=0

-cos2x=0

x=П/4+Пk/2

ctgx+tgx=4

sin^2x+cos^2x=4sinxcosx

1/2=sin2x

2x=(-1)^kП/6+пk

x=(-1)^kП/12+Пk/2