1.

Find the value of (p + q)2, if p + q Cot3 α = Cot α.Cosec α and q = p tan α.1). 1 + Cos α2). 1 + Sin 2α3). 1 – cos 2α4). 1 - Sin α

Answer»

p + q COTα = Cot α.Cosec α

⇒ p + q COSα/Sin3 α = Cos α/Sinα

Putting q = p TAN α in the equation we get

⇒ p + p tan α.(Cosα/Sin3 α) = Cos α/Sinα

Putting tan α = sin α /cos α and simplifying we get

⇒ p(1 + Cosα/Sinα ) = Cos α/Sinα

⇒ p = Cos α

Putting that in q = p tan α we get q = Sin α

Here (p + q)2 = (Sin α + Cos α)2

Using (a + b)2 = a2 + b2 + 2AB we get

(p + q)2 = Sin2 α + Cos2 α + 2 Sin α.Cos α

Using Sin2 α + Cos2 α = 1 and 2 Sin α.Cos α = Sin 2α

We get (p + q)2 = 1 + Sin 2α


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