prove that sen^2(x) = 1/2 - 1/2 cos(2x)?

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2007-10-26 06:57:18 · 3 answers · asked by Hans 1 in Science & Mathematics ➔ Mathematics

1/2 - 1/2 cos(2x) = 1/2 (1 - cos(2x)) = 1/2( 1 - (cos^2(x) - sin^2(x)) = 1/2(sen^2(x) + cos^2(x) - cos^2(x) + sin^2(x)) = 1/2(2 sin^2(x) = sin^2(x)

2007-10-26 07:09:15 · answer #1 · answered by Steiner 7 · 0⤊ 1⤋

cos^(2)x + sin^(2)x = 1
cos^(2)x - sin^(2)x = cos[2x]

these are known (standard) results: subtract lh and rh sides to get a new result:simplify it.

2007-10-26 14:10:26 · answer #2 · answered by anthony@three-rs.com 3 · 0⤊ 0⤋

Yep

2007-10-26 14:05:37 · answer #3 · answered by Anonymous · 0⤊ 0⤋