First I attempted to ipmlicitly differentiate(adsbygoogle = window.adsbygoogle || []).push({});

c2 = a2 + b2 -2abcos(theta)

da/db

I almost got the correct solution according to MIT's key, however I missed one part. The cos from the original function remained cos, and I had differentiated it to -sin.

I'm just wondering why it remained cos instead of being differentiated?

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# Homework Help: Very Quick Differentiation Question

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