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# New Maths 9-1 GCSE Question watch

1. ACB is a straight line.
A is the point (0, 8), and B is the point (4, 0)
C is the midpoint of AB.
Line DCE is perpendicular to line ACB.

Work out the equation of line DCE.
------------------------------------------------------------------------
What I did was:
I worked out that mAB = -2, therefore mDCE = 1/2
The midpoint of AB(which is C) is (2,4)
I then substituted (2,4) into y = 1/2x +c
This gave me y = 1/2x +3 as the equation of the line DCE.

I checked the mark scheme and their answer is y = 1/2x -2.
I was doing another of their questions and the mark scheme was definitely wrong then.

Was my method/answer correct, if not, where did I go wrong?
2. (Original post by bintabii)
ACB is a straight line.
A is the point (0, 8), and B is the point (4, 0)
C is the midpoint of AB.
Line DCE is perpendicular to line ACB.

Work out the equation of line DCE.
------------------------------------------------------------------------
What I did was:
I worked out that mAB = -2, therefore mDCE = 1/2
The midpoint of AB(which is C) is (2,4)
I then substituted (2,4) into y = 1/2x +c
This gave me y = 1/2x +3 as the equation of the line DCE.

I checked the mark scheme and their answer is y = 1/2x -2.
I was doing another of their questions and the mark scheme was definitely wrong then.

Was my method/answer correct, if not, where did I go wrong?
Your answer is definitely correct. (2,4) isn't even a point on their line.
3. (Original post by SeanFM)
Your answer is definitely correct. (2,4) isn't even a point on their line.
Thanks for checking!
4. (Original post by bintabii)
ACB is a straight line.
A is the point (0, 8), and B is the point (4, 0)
C is the midpoint of AB.
Line DCE is perpendicular to line ACB.

Work out the equation of line DCE.
------------------------------------------------------------------------
What I did was:
I worked out that mAB = -2, therefore mDCE = 1/2
The midpoint of AB(which is C) is (2,4)
I then substituted (2,4) into y = 1/2x +c
This gave me y = 1/2x +3 as the equation of the line DCE.

I checked the mark scheme and their answer is y = 1/2x -2.
I was doing another of their questions and the mark scheme was definitely wrong then.

Was my method/answer correct, if not, where did I go wrong?
I can also confirm that you are right. Logic is flawless - either way plot it, work it out algebraically, same answer.
5. (Original post by CraigFowler)
I can also confirm that you are right. Logic is flawless - either way plot it, work it out algebraically, same answer.
Thanks!

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Updated: February 19, 2017
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