Answers

2014-07-15T13:00:56+05:30
Given xSinA – yCosA = 0
⇒ x.SinA = y CosA     ........(1)

Consider 
xSin^3A+yCos^3A = SinACosA

 xSin^3A+yCosACos^2A = SinACosA

 xSin^3A+ xSinACos^2A = SinACosA     {From eq 1}

xSin^3A+ xSinA(1-Sin^2A) = SinACosA

xSin^3A+ xSinA-xSin^3A = SinACosA

xSinA = SinACosA

x = CosA          ......(2)

Substitute this value in the eq (1)
 
We get y = SinA

so, x^2 + y^2 = Cos^2A + Sin^2A = 1 
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