Answers

2014-02-01T19:51:26+08:00
Let x=sin A

The equation is "equivalent" to:
 x^{2} -1 over x+1 = x-1

Multiplying x+1 to both sides gives:
 x^{2} -1=(x+1)(x-1)

Since  a^{2} - b^{2} =(a+b)(a-b),
Therefore,
 x^{2} -1= x^{2} -1
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