1.

Show that :(1 - sin A + cos A)^2= 2 (1 - sin A) (1 + cos A)​

Answer»

\underline {\large \pmb{\mathfrak{๑ \: Question:}}}

SHOW that :

\rm{(1-sinA+cosA)^2=2(1-sinA)(1+cosA)}

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\large \underline {\pmb{\mathfrak{๑ \: Solution:}}}

  • \rm (1-sinA+cosA)^2=LHS

  • \rm 1+sin^2A+cos^2A-2sinA-2sinAcosA+2cosA

  • \rm 1+1-2sinA-2sinAcosA+2cosA

  • \rm 2+2cosA-2sinA-2sinAcosA

  • \rm 2(1+cosA)-2sinA(1+cosA)

  • \rm (1+cosA)(2-2sinA)

  • \rm 2(1+cosA)(1-sinA)=RHS

\underline {\pmb{\mathfrak{Hence,~proved!}}}

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\large \underline{\pmb{\mathfrak{๑~More~to~know:}}}

  • \rm cos^2\theta +sin^2\theta=1

  • \rm 1+tan^2\theta=sec^2\theta

  • \rm 1+cot^2\theta=cosec^2\theta

  • \rm cosec(x \pm 2\pi)=cosecx

  • \rm tan(x \pm \pi)=tanx

  • \rm sin(x \pm y)=sinx~cosy \pm cosx~siny

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