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Write the value of cos^2 76^@+cos^2 16^@...

Write the value of `cos^2 76^@+cos^2 16^@- cos76^@ cos16^@`

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`cos^2 76° + cos^2 16° – cos 76° cos 16°`

Multiplying and dividing by 2,

= `(1/2) [2 cos^276° + 2 cos^216° – 2 cos 76° cos 16°]`

Using the formulas `2 cos^2x = cos ^2x + 1 and cos x cos y = cos(x + y) + cos(x – y),`

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