Literal created by ChatGPT4o:
[
u^2 \Bigg|_0^{\frac{\pi}{4}} = \left( \frac{\sqrt{2}}{2} \right)^2 - 0^2 = \frac{2}{4} - 0 = \frac{1}{2}.
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Renders broken in the chat but renders correctly in an online LaTex renderer such as overleaf dot com. Properly rendered LaTex with broken LaTex scattered in between has been an ongoing and frequent issue with at least calculus and trig related syntax.