MATHS P 3 HELP MJ 08

[AndrewCedric]

Number 5 part 2
How do you get 1/4???

http://www.srepapmaxeeeerf.org/A%20Level/Maths/CIE/2008%20Jun/9709_s08_qp_3.pdf

[Twinkle Charms]

1/z=1/(2costheta+i(1-2sintheta))
1/(z+2-i)=1/[2costheta+i(1-2sintheta)+2-i]
            =1/[(2costheta+2)+i(1-2sintheta-1)]
            =1/[2(1+costheta)+i(-2sintheta)]
            =1/[2(1+costheta-isintheta) * conjugate of the denominator/conjugate of the denominator


solve this ull reach to
1+costheta/[4(1+costheta) + isintheta/4(1+costheta) = 1/4 + i sintheta/4(1+costheta)


therfore real part is 1/4 which is a constant...

get it? if u have problem with the conjugation do tell...           

[AndrewCedric]

THANKS A LOT !!!!!!!!!!

Yea no more problems.
At first, I omitted the i in the denominator cause i think it wont be needed for the answer.
So i guess, you have to just plug all of them in and
finally simplify the Real part at the end only..

THANKS AGAIN !!!!!
Good Luck for Stats and Maths P3 if you're taking those !!

[Twinkle Charms]

yea im taking those as well Thank You =)