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| 1. |
Cosx cosx -sinx sinx =cos2x how |
| Answer» If we multiply cosxcosx =cos²x. Sinxsinx = sin²xnow, we sub.Cos²x-sin²x = cos2x and it is a formula.If we take only in cos then, cos 2x = cos²x -1+cos²x= 2cos²x-1 | |