cos²θ/2 - sin²θ/2 = cosθ
Cosine addition formula:
cos (x + y) = cosxcosy - sinxsiny
L.S. = cos²θ/2 - sin²θ/2
R.S. = cosθ
= cos (θ/2 + θ/2)
= (cosθ/2)(cosθ/2) - (sinθ/2)(sinθ/2)
= cos²θ/2 - sin²θ/2
Since L.S(Lefthand side of the equation) is equal to R.S(Rigthandside of the equation), therefore the identity is verified.
It's true. Verification is at http://www.wolframalpha.com/input/?i=cos%C2%B2(%C3...
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Verified answer
cos²θ/2 - sin²θ/2 = cosθ
Cosine addition formula:
cos (x + y) = cosxcosy - sinxsiny
L.S. = cos²θ/2 - sin²θ/2
R.S. = cosθ
= cos (θ/2 + θ/2)
= (cosθ/2)(cosθ/2) - (sinθ/2)(sinθ/2)
= cos²θ/2 - sin²θ/2
Since L.S(Lefthand side of the equation) is equal to R.S(Rigthandside of the equation), therefore the identity is verified.
It's true. Verification is at http://www.wolframalpha.com/input/?i=cos%C2%B2(%C3...