If x sin (a + y) + sin a cos (a + y) = 0, prove that 
Given: x sin(a + y) + sin a cos(a + y) = 0
⇒ x = - sin a cot (a + y) 
Differentiating with respect to y, we get
Hence Proved
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If x sin (a + y) + sin a cos (a + y) = 0, prove that
Given: x sin(a + y) + sin a cos(a + y) = 0
⇒ x = - sin a cot (a + y)
Differentiating with respect to y, we get
Hence Proved