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If cosA=3√2/5,then show that cos2A=11/25
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If cosA=3√2/5,then show that cos2A=11/25

User Ramprasath Selvam
by
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1 Answer

5 votes

Answer:

Explanation:

Cos 2A = 2Cos² A - 1


= 2*((3√(2))/(5))^(2)-1\\\\=2*((3^(2)*(√(2))^(2))/(5^(2)))-1\\\\=2*(9*2)/(25) - 1\\\\=(36)/(25)-1\\\\=(36)/(25)-(25)/(25)\\\\=(11)/(25)

User Svinec
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