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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: Halil on November 10, 2011, 08:46:46 pm

Title: cartesian equation?
Post by: Halil on November 10, 2011, 08:46:46 pm: orite i had a function like sin(t)i+cos(2t)j and it asked for the cartesian equation

dont you make sin(t)=x and cos(2t)=y, then make t subject in term of x and sub that into the cos(2t)=y?

am i right or wrong?
Title: Re: cartesian equation?
Post by: tony3272 on November 10, 2011, 08:50:16 pm: I'm not sure if that works but using your double angle formula: $y=cos(2t)=1-2sin^2(t)$

and since $x=sin(t)$ We just go: $y=1-2x^2$
Title: Re: cartesian equation?
Post by: Halil on November 10, 2011, 08:52:05 pm: ohhhhhhh, thanks for enlightening my mind about that mate,