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# measuring lines from a tangent in a circle CCEA C2 watch

1. In this question you have to find the area of thr kit. When finding the length of side AC. BC is taken to be 5. After using calculations i get the radius to be 4 and cannot understand why the length used is 5. Point C also has coordinates of (3,-5) using the circle equation to work it out. The radius is also 4 on the markscheme but 5 is still used as the lengthbof BC can someone help me out? Thanks

2. I think that's how you do it, didn't check over it but I think it's right? What did you get?
3. (Original post by GlitchKid)

In this question you have to find the area of thr kit. When finding the length of side AC. BC is taken to be 5. After using calculations i get the radius to be 4 and cannot understand why the length used is 5. Point C also has coordinates of (3,-5) using the circle equation to work it out. The radius is also 4 on the markscheme but 5 is still used as the lengthbof BC can someone help me out? Thanks
Might be a mistake? I got BC to be 4 too.
4. No those are the same answers as the mark scheme, but why do you take BC to be 5 and not 4 in your triangle? I can see how (by making a triangle out of both coords) but then the triangle doesn't make since as BC must be 4 as it is radius but to find AC you take it to be 5
5. (Original post by GlitchKid)
No those are the same answers as the mark scheme, but why do you take BC to be 5 and not 4 in your triangle? I can see how (by making a triangle out of both coords) but then the triangle doesn't make since as BC must be 4 as it is radius but to find AC you take it to be 5

Is that what you mean? The 5 was from the coordinates of the centre point. To work out length of AC, you don't need the length of BC.
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6. Yes so then you arent using the triangle given you are creating your own with the corordinates given?
7. (Original post by GlitchKid)
Yes so then you arent using the triangle given you are creating your own with the corordinates given?
To find out the length of AC, I create a new triangle to find out that length. Then once I've got AC, and I have BC already so I can find out AC, then find out the area of the triangle they are asking for. Hope that makes sense.
8. Yea thats akriggt i understand it now, thanks
9. (Original post by GlitchKid)
Yea thats akriggt i understand it now, thanks
No problem, feel free to give me +Rep if I helped

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