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sin5A=5cos^4AsinA-10cos^2Asin^3A+sin^5A...

`sin5A=5cos^4AsinA-10cos^2Asin^3A+sin^5A`

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`L.H.S. = sin5A = sin(3A+2A) = sin3Acos2A+sin2Acos3A`
`=(3sinA-4sin^3A)(1-2sin^2A)+(4cos^3A-3cosA)(2sinAcosA)`
`=3sinA-6sin^3A-4sin^3A+8sin^5A+8cos^4AsinA - 6sinAcos^2A`
`=sin^5A+5cos^4AsinA-10cos^2Asin^3A = R.H.S.`
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RD SHARMA-TRIGONOMETRIC RATIOS OF MULTIPLE AND SUBMULTIPLE ANGLES-Solved Examples And Exercises
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  9. Prove that: (cos2theta)/(1+sin2theta)=tan(pi/4-theta)

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  11. Prove that: (1+sintheta-costheta)/(1+sintheta+costheta)=tan(theta/2)

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  12. Prove that: (costheta)/(1+sintheta)=tan(pi/4-theta/2)

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