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In DeltaABC, prove that: cos2A+cos2B-c...

In `DeltaABC`, prove that:
`cos2A+cos2B-cos2C=1-4sinAsinBcosC`

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AI Generated Solution

To prove the equation \( \cos 2A + \cos 2B - \cos 2C = 1 - 4 \sin A \sin B \cos C \) in triangle \( \Delta ABC \), we will follow these steps: ### Step 1: Use the angle sum property of triangles In triangle \( ABC \), we know that the sum of angles is \( A + B + C = 180^\circ \). Therefore, we can express \( C \) as: \[ C = 180^\circ - (A + B) \] ...
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