kenneyfamily
MAJOR HELP PLEASE!!
Verify that the equation is an identity. Show all your work.
(sin x + cos x)^2  1 = sin 2x



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nubeer
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(a+b)^2 =a^2+2ab+b^2
so
(sin x + cos x)^2  1
sin^2x+2sinxcosx+cos^2x 1
2sinxcosx +sin^2x+cos^2x 1
i think u can do from here.

tamtoan
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use formula \[(a+b)^{2} = a^{2} + 2ab + b^{2}\], expand that out and you will see what you need to

kenneyfamily
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@nubeer i'm sorry i am a little lost, could you please explain further?

nubeer
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2sinxcosx +sin^2x+cos^2x 1
have you understood how i have got this part?

kenneyfamily
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yes with the formula right?

nubeer
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2sinxcosx +sin^2x+cos^2x 1
what is sin^2x+cos^2x = ?

kenneyfamily
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1?

nubeer
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yes.. now put this 1 in the equation
2sinxcosx +sin^2x+cos^2x 1
2sinxcosx +11.. got it?

nubeer
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@kenneyfamily so?

kenneyfamily
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2sinxcosx

kenneyfamily
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@nubeer right?

nubeer
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yes
and 2sinxcosx=sin2x (according to the identity)

kenneyfamily
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you're awesome..thanks!!!