sorry burem tapi tolong bantuannya, itu lim mendekati pi/4

Lim Cosx - Sinx / 2x - π/2
x→π/4

Turunkan / L'hospital
Lim -sinx - Cosx / 2
x→π/4

-Sin45° - Cos45° / 2
-½√2 - ½√2 / 2
-√2 / 2
atau -½√2

Lim (cos x - sin x)/(2x - π/2)
= Lim (cos x - sin x)/(2x - π/2) . (cos x + sin x)/(cos x + sin x)
= Lim (cos^2 x - sin^2 x)/(2x - π/2)(cos x + sin x)
= Lim (cos 2x) / (2x - π/2)(cos x + sin x)
= Lim (sin (π/2 - 2x)) / -1(π/2 - 2x)(cos x + sin x)
= Lim 1/(cos x + sin x) . (sin (π/2 - 2x))/-1(π/2 - 2x)
= 1/(cos π/4 + sin π/4) . 1/-1
= 1/(1/2 √2 + 1/2 √2) . -1
= -1/(√2)
= -1/√2 . √2/√2
= (-1/2) √2