C1 help pls again heh

CorpusLuteum

How did they do part iv

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Reply 1

whitedwarf

I can't view the image
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(edited 7 years ago)

Original post by CorpusLuteum

How did they do part iv

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which year is it ?

Original post by h3rmit

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Original post by whitedwarf

I can't view the image
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I attached it again

Reply 6

CorpusLuteum

Original post by mgy2000

which year is it ?

2014 june OCR MEI

Reply 7

RegrettingAS

First find the coordinates for d. Then use y-y1=m(x-x1) by subbing in A and D's coordinates and then you can find m. Then sub in m and d coordinates into y=mx+c and find c. Final form will be y= (your m)x+(Your c)

Reply 8

OneandOnly123

work out the gradient of bc
flip the fraction and put a negative as ad is the negative reciprocal of bc , this will give u gradient of ad
y-y1=m(x-x1) where m is gradient and sub the coordinates of c and there u hv it

Reply 9

SherlockHolmes

Original post by CorpusLuteum

...

Find the gradient of the line AD and call this m. Then the gradient of the tangent line at D is the negative reciprocal of m.

Reply 10

h3rmit

Original post by CorpusLuteum

I attached it again

Find the gradient of AC or AD or DC, and use that in y=mx+c

Reply 11

CorpusLuteum

Original post by h3rmit

Find the gradient of AC or AD or DC, and use that in y=mx+c

but why?

Reply 12

h3rmit

Original post by CorpusLuteum

but why?

So you can pass your maths exams, get into a good uni, get a good job and be prepared for life? I'm not really sure what justifcation you're looking for

Reply 13

klm7

I do OCR without the MEI so idk if you would do it the same way as me but I hope this helps :smile:

Find the gradient of the line AD as this will be perpendicular to the tangent that you need to find.
(4-0)/(7-1) = 2/3
The gradient of the tangent will be the negative reciprocal of this. (Because they are perpendicular to each other)
-3/2
Put this gradient into a straight line equation
y=mx+c
y=-3/2x+c
Substitute your x and y for D in to work out c
4=-3/2(7) + c
c=14.5

So y=(-3/2)x+14.5

(edited 7 years ago)

Reply 14

TheConfusedMedic

Work out the gradient of AD. The gradient of the tangent at D is the negative reciprocal of this since you know that a tangent is perpendicular to a diameter (or radius). From there you should be able to work out the equation of the line :smile:

Reply 15

CorpusLuteum

Original post by h3rmit

So you can pass your maths exams, get into a good uni, get a good job and be prepared for life? I'm not really sure what justifcation you're looking for