Question
Let $A, B,$ and $C$ be the angles of a triangle, so that $A+B+C=\pi$(a) Show that $\sin (A+B)=\sin C$(b) Show that $\cos (A+B)=-\cos C$(c) Show that $\tan (A+B)=-\tan C$
Step 1
We can rewrite this as $A+B=\pi-C$. Show more…
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