someone help pls urgent Watch

penelopecrux
Badges: 14
Rep:
?
#1
Report Thread starter 2 years ago
#1
can someone help me on this question.
prove that =
sin^3x - cos^3x/(sinx - cosx) is identical to 1 + 0.5sin2x
0
reply
RDKGames
Badges: 20
Rep:
?
#2
Report 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
reply
penelopecrux
Badges: 14
Rep:
?
#3
Report Thread starter 2 years ago
#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
reply
Nada Billy
Badges: 1
Rep:
?
#4
Report 2 years ago
#4
Use the identities
0
reply
penelopecrux
Badges: 14
Rep:
?
#5
Report Thread starter 2 years ago
#5
(Original post by Nada Billy)
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
reply
RDKGames
Badges: 20
Rep:
?
#6
Report 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
reply
penelopecrux
Badges: 14
Rep:
?
#7
Report Thread starter 2 years ago
#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
reply
RDKGames
Badges: 20
Rep:
?
#8
Report 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
reply
penelopecrux
Badges: 14
Rep:
?
#9
Report Thread starter 2 years ago
#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
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts

All the exam results help you need

906

people online now

225,530

students helped last year

University open days

  • University of Aberdeen
    General Open Day Undergraduate
    Tue, 27 Aug '19
  • Norwich University of the Arts
    Postgraduate (MA) Open Day Postgraduate
    Sat, 31 Aug '19
  • University of Lincoln
    Guardian Offices, Kings Cross, London Postgraduate
    Mon, 2 Sep '19

How are you feeling about GCSE Results Day?

Hopeful (220)
12.48%
Excited (165)
9.36%
Worried (308)
17.47%
Terrified (389)
22.06%
Meh (182)
10.32%
Confused (38)
2.16%
Putting on a brave face (244)
13.84%
Impatient (217)
12.31%

Watched Threads

View All