Qualification > Math

Maths P1 doubt on markscheme

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cashem'up:

--- Quote from: nid404 on May 09, 2010, 06:47:15 am ---yup. Faster  ;)

--- End quote ---

hey thanks guy nid404 and gladiator......... i did the same as wat nid did ...... by the periodicity method however in the 2nd method i attempted i am getting 4 answers where  took cos2x is taken common... how is it wrong......

nid404:
can you show how you derived your answer?

I can then help rectify

Meticulous:
Use periodicity when you're PERFECT at using it. Other wise you'll lose track.

cashem'up:

--- Quote from: nid404 on May 09, 2010, 07:59:51 am ---can you show how you derived your answer?

I can then help rectify

--- End quote ---

see i have
sin 2x + 3cos2x = 0
now if i take cos 2x common then
cos2x(sin2x/cos2x +3)
so cos2x(tan2x+3)=0
now one ans is tan2x= -3 and as u did by the periodicity method above get 2 answers
however another would also be cos2x=0 and so u get 2 more answers 45 and 135...................... would that be correct i dont find nethin wrong in it except the fact that its not in the MS

nid404:
wait...how on earth do you get cos2x=0 ?

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