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# cos(a+b) = (cos a)(cos b)-(sin a)(sin b) యొక్క నిరూపణ

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Title -Proof: cos(a+b) = (cos a)(cos b)-(sin a)(sin b)
URL -https://www.khanacademy.org/math/trigonometry/less-basic-trigonometry/trig_iden_tutorial/v/proof--cos-a-b-----cos-a--cos-b---sin-a--sin-b