Question

under root 2 + under root 2 + 2 cos 4 theta = 2 cos theta​

Answer 1

√[2+√{2+2cos4a}=

√[2+√{2(1+cos2.2a)}. ]

√[2+√{2.2cos²2a}

√[2+2cos2a]

√[2(1+cos2a)]

√(2.2cos²a)=2cosa.

proved.

formula:-- cos2a=2cos²a -1

1+cos2a=2cos²a

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