Prove that ,Cos(60°+A)+cos(60°-A)-cosA=0

1.	Prove that ,Cos(60°+A)+cos(60°-A)-cosA=0
Answer» $\underline{\textsf{To <klux>PROVE</klux>:}}$ $\mathsf{cos(60^{\circ}+A)+cos(60^{\circ}-A)-cosA=0}$ $\underline{\textsf{Solution:}}$ $\textsf{Consider,}$ $\mathsf{cos(60^{\circ}+A)+cos(60^{\circ}-A)-cosA}$ $\textsf{Using the identities}$ $\boxed{\mathsf{cos(A+B)=cosA\,cosB-sinA\,sinB}}$ $\boxed{\mathsf{cos(A-B)=cosA\,cosB+sinA\,sinB}}$ $\mathsf{=cos60^{\circ}\,cosA-sin60^{\circ}\,sinA+cos60^{\circ}\,cosA+sin60^{\circ}\,sinA-cosA}$ $\mathsf{=2\,cos60^{\circ}\,cosA-cosA}$ $\mathsf{=2(\dfrac{1}{2})\,cosA-cosA}$ $\mathsf{=cosA-cosA}$ $\mathsf{=0}$ $\implies\boxed{\mathsf{cos(60^{\circ}+A)+cos(60^{\circ}-A)-cosA=0}}$ FIND more: Prove that 1-sin^2x/1+cotx-cos^2x/1+tanx=sinxcossx brainly.in/question/4927186 TAN(π/4+x)-tan(π/4-x)=2TAN 2x brainly.in/question/10999329

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$\underline{\textsf{To <klux>PROVE</klux>:}}$