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How would I solve the following question?

Show that

$$2\sin(127.5)\sin(97.5)=(\sqrt{3}+\sqrt{2})/2$$

My work is I know

$$\sin A\sin B=(-1/2)(\cos(A+B)-\cos(A-B))$$

So I did

$$(-1/2)(\cos(127.5+97.5)-\cos(127.5-97.5))$$

but I do not get the correct answer.

  • 1
    What do you get?2012-08-03

2 Answers 2