# someone help pls urgentWatch

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#1
can someone help me on this question.
prove that =
sin^3x - cos^3x/(sinx - cosx) is identical to 1 + 0.5sin2x
0
2 years ago
#2
(Original post by penelopecrux)
can someone help me on this question.
prove that =
sin^3x - cos^3x/(sinx - cosx) is identical to 1 + 0.5sin2x
Long division first and then use identities.
0
#3
(Original post by RDKGames)
Long division first and then use identities.
yeah i know
so would 1+ 0.5 sin2x be equal to x^2 + xy +y^2
0
2 years ago
#4
Use the identities
0
#5
Use the identities
so far i did:

sin^2x + sinxcosx + cos^2x is identical to 1 + 0.5sin2x
and this would be 1 + sinxcosx but im not sure if sinxcosx is identical to 0.5sin2x....?
0
2 years ago
#6
(Original post by penelopecrux)
so far i did:

sin^2x + sinxcosx + cos^2x is identical to 1 + 0.5sin2x
and this would be 1 + sinxcosx but im not sure if sinxcosx is identical to 0.5sin2x....?
Of course it is. Look at the identity for sin(2x) and divide both sides by 2.
0
#7
(Original post by RDKGames)
Of course it is. Look at the identity for sin(2x) and divide both sides by 2.
okay cool got that, so how would i also get...

hence solve the eqaution for 0 < x< 2 pi
sin^3x - cos^3x = sinx -cosx
0
2 years ago
#8
(Original post by penelopecrux)
okay cool got that, so how would i also get...

hence solve the eqaution for 0 < x< 2 pi
sin^3x - cos^3x = sinx -cosx
Divide both sides by the RHS. Replace LHS by your new result from previous part. Proceed to solve as usual.
0
#9
(Original post by RDKGames)
Divide both sides by the RHS. Replace LHS by your new result from previous part. Proceed to solve as usual.
thanks so much i get it now
0
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