Answer:
-√2
Step-by-step explanation:
For the typing purpose I replaced θ with n in the calculation
[tex]\lim_{n \to \frac{\pi }{4}} \frac{cos n-sin n}{\frac{\pi }{4} } ...limits L'Hopital's Rule\\= \lim_{n \to \frac{\pi }{4}} \frac{-sin n-cos n}{1 } ... plug. in . \frac{\pi }{4} \\= - sin \frac{\pi }{4} - cos \frac{\pi }{4}\\= - \frac{\sqrt{2} }{2} - \frac{\sqrt{2} }{2}\\= \frac{- 2\sqrt{2}}{2} \\= - \sqrt{2}[/tex]