[TENTANG LIMIT TRIGONOMETRY] Cara nya bagaimana? Mohon bantuannya kakak kakak yang jenius

Bab Limit
Matematika SMA Kelas X

lim (cos 2x / (sin x – cos x))
x→π/4

= lim ((cos² x – sin² x) / ( – (cos x – sin x))
  x→π/4

= lim ((cos x + sin x) (cos x – sin x) / ( – (cos x – sin x))
 x→π/4

= – (cos π/4 + sin π/4)
= – (1/2 √2 + 1/2 √2)
= – √2

jawabannya E