Fix typo

[durable-vest]

The squeeze theorem blog post states

why does −x ≤ x sin⁡(x) ≤ x imply that −∣x∣ x ≤ sin⁡(x) ≤ ∣x∣ when x ≥ 0?

...when it's probably meant to say:

why does −x ≤ x sin⁡(x) ≤ x imply that −∣x∣ ≤ x sin⁡(x) ≤ ∣x∣ when x ≥ 0?

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Not tested, I couldn't figure out how to generate the pages

btw thanks for writing up this blog post it will save me in my calculus test tomorrow