Lim x-> phi/4= 1-2sin 2x/ cosx-sinx

Lim (x->π/4)  (1 – 2 sin² x) / (cos x – sin x )
substitusi x = π/4 –> bentuk 0/0

(1 – 2 sin² x ) / (cos x – sin x )=
= (cos x – sin x)²/ (cos x – sin x )
= cos x – sin x
x = π/4  –>limit = (cos π/4 – sin π/4)
limit = 1/2 √2 – 1/2 √2
limit = 0