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Adolfo Adams

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3y ago
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12y ago

sin2x=sinxcosx+cosxsinx= 2sinxcosx

sin2x*-1=-sin2x

2sinxcosx*-1=-2sinxcosx

-sin2x=-2sinxcosx

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Q: Why does -2sinxcosx equal -sin2x?
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What does sin2x - 1 equal?

1


Is sin2x equal to sin2x?

sin2X = sin2X What is it about ' equation ' you do you not understand. Of course they are equal!


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Start by squaring both sides of the equation to get, (sinx + cosx)2 = 0.25 Simplify the left side to get sin2x + 2sinxcosx + cos2x = 0.25 Using the Pythagorean identity gets 2sinxcosx + 1 = 0.25 2sinxcosx = -0.75 Using the double angle formula gets Sin(2x) = -0.75 Take the arcsin to get 2x = sin-1(-0.75) x = sin-1(-0.75)/2 Now, a scientific calculator can be used to find the solutions.


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How does sin2x divided by 1-cosx equal 1 plus cosx?

sin2x / (1-cos x) = (1-cos2x) / (1-cos x) = (1-cos x)(1+cos x) / (1-cos x) = (1+cos x) sin2x=1-cos2x as sin2x+cos2x=1 1-cos2x = (1-cos x)(1+cos x) as a2-b2=(a-b)(a+b)


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