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Trignometry

dhilipan1995

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6 Dec 2011 21:22:43 IST

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how sin sq 9A)-sin sq(b)= sin(A+B). sin(A-B) ???????

Mathematics

How sin²A-sin²B=sin(A+B). sin(A-B) ? ?

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Sumiran agrawal

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26 Jan 2012 21:28:47 IST

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sin^2A-sin^2B=sin(A-B)sin(A+B)

Taking R.H.S

sin(A-B)sin(A+B)

(sinAcosB-cosAsinB)(sinAcosB+sinBcosA)

sin^2Acos^2B-cos^2Asin^2B

sin^2A(1-sin^2B) - (1-sin^2A)sin^2B

sin^2A - sin^2Asin^2B - sin^2B + sin^2Asin^2B

sin^2A - sin^2B

= L.H.S

Proved........

gauti95

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Joined: 26 Jan 2012

Posts: 46

26 Jan 2012 21:55:30 IST

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its so easy

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