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If A+B=X prove that cos^2A+cos^2B+cos^2X=1+2cosA.cosB.cosX?

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  • If A+B=X prove that cos^2A+cos^2B+cos^2X=1+2cosA.cosB.cosX?


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Prove that sin^2A ×cos2B - sin^2B ... sin^2B×cos2A = cos ^2B - cos^ 2A? ... .cos(b) - sin(a).sin(b) → suppose that: a = b = x cos(x + x) = cos(x).cos(x ...
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Positive: 48 %
If A+B+C=180 prove that cos^2a+cos^2B+cos^2C=1 ... cos 2x &=& 2\cos^2x-1 \end ... cos(A+B-A+B)) \\ &=&1+\cos^2C+\frac{1}{2}(\cos 2A+\cos 2B) ...
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Positive: 45 %

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Problems about trigonometry. READ THIS FIRST ; ... a+b+c=pi Prove that cos(2a)+cos(2b) ... Prove that cos(a).cos(a) + cos(b) ...
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Positive: 48 %
Useful formulas. It's not always easy ... sin 2 A + cos 2 A = 1: sin 2 A = (1 - cos 2A)/2: ... If y = a x 2 + b x + c then ... x = [ -b ± √( b 2 - 4 a c
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Positive: 43 %
Verify (sin B - cos B)(sin B + cos B) ... 1 - (cos^2B - sin^2 B) = - (1 - 2sin^2 B) - cos (2B) = - cos (2B) Reminder: cos 2a = 1 - 2sin^2a = cos^2 a - sin ...
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Positive: 29 %
Trigonometric and Geometric Conversions ... cos 2 A + sin 2 A = 1. ... The proof above leads to an interesting fact about angles in circles.
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Positive: 6 %

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