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C1 and C2 DOUBTS HERE!!!!!

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Summer :]:

--- Quote from: Khey on May 04, 2010, 06:09:04 pm ---(a) For a triangle ABC, show that
   (i) AB is perpendicular to BC
   (ii) BM = CM, where M is the midpoint of AC
(b) Find also an equation of circle passing through A, B & C

--- End quote ---

(b)
the equation of the circle is (x-h)^2 + (y-b)^2 = r^2
where (h,x) is the midpoint of the circle and r = radius of the circle
substitute the values of A (1,3) in the place of (x,y) in the equation..
like this
(1-h)^2 + (3-b)^2 = r^2
do the same with points B and C
with B : (5-h)^2 +(9-b)^2 = r^2
with C : (8-h)^2 + (7-b)^2 - r^2

the radius of the circle is the same
therefore all the equations above should be equal

(1-h)^2 + (3-b)^2 = (5-h)^2 + (9-b)^2 = (8-h)^2 + (7-b)^2
rearrange them and you'll get one of the values of either h or B
then subsitute this value to get the other values
you'll get the midpoint of the circle
all you need is the radius now
so use one of the points example A which is (1,3)
(1-h)^2 +(3-b)^2 = r^2
to get it since you have the values of the midpoint (h,b) which u would've have obtained previously  ::)

Monica:
Too many sticky topics like that.

You can make it sticky the day b4 the exam, other than that its been there for 10 days and no one posted.

Blizz_rb93:
No it's good to be sticky before 10 days! Cause people don't study a day before the exam so once they have questions they start posting!! I'm preparing some questions for C1 but please don't close the forum or move it or smthn :p
trust me ppl will start posting soon :D

wakemeup:


http://www.srepapmaxeeeerf.org/A%20Level/Maths/Edexcel/C1/C1%202008-01.pdf

Q7 (d)
Q10 (a)

vanibharutham:
7d)

u have to find x4 to get the sequence

x1 = 1
x2 = -0.5
x3 = 1
x4 = -0.5

see the sequence?
all evens are -0.5
all odds are 1

therefore x2008 = -0.5
Its a repeating sequence


10a)

hmm

easy way to do this:

you know that the curve will cross the x-axis when y = 0
therefore, x = -3 and x = 1

You should also note that it is a cubic function

and that when x = 0 , y = 3

you know have three points

(0,3) (-3,0) and (1,0)

make sure it goes through those points and that it is cubic

here is a sketch:
http://www.wolframalpha.com/input/?i=plot+x%C2%B3+%2B+x%C2%B2+-5x+%2B+3

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