Hello_World
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- Jun 22, 2022
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What did you get for length of OD? (1a)View attachment 33418
For question 3 b) how do I find the value of k after I found OH
and I have the same problem for 3d) as well, I don't know what to do to find m and n
help appreciated thanks
In order to help, we need to see what expression you got for [imath]\overrightarrow{OH}[/imath]. You can't find k unless you have the right expression.View attachment 33418
For question 3 b) how do I find the value of k after I found OH
and I have the same problem for 3d) as well, I don't know what to do to find m and n
help appreciated thanks
The marks you made on your diagram seem to indicate that you are taking AH = 1 and HD = k. This is not necessarily true. It could be that OH = 2 and HC = 2k. If you hadn't been given any lengths in the problem you would be okay to do this but you are given that OA = 2 and OB = 3. So the length scale is already set.View attachment 33418
For question 3 b) how do I find the value of k after I found OH
and I have the same problem for 3d) as well, I don't know what to do to find m and n
help appreciated thanks
I'm assuming those marks weren't meant to show actual lengths, but just reminders of the ratios. But I agree they are misleading, just as it is to write a as if it were a length.The marks you made on your diagram seem to indicate that you are taking AH = 1 and HD = k. This is not necessarily true. It could be that OH = 2 and HC = 2k. If you hadn't been given any lengths in the problem you would be okay to do this but you are given that OA = 2 and OB = 3. So the length scale is already set.
-Dan
I finally sat down and worked out a solution to part b. The formula for [imath]\overrightarrow{OH}[/imath] is based on looking only at triangle AHD in terms of vectors, and not using m or n at all. Then we can find k by using the fact that [imath]\overrightarrow{OH}\perp\overrightarrow{AB}[/imath]. Assuming you know about the dot (scalar) product, you are essentially told what [imath]\overrightarrow{a}\cdot\overrightarrow{b}[/imath] is, and you can work out [imath]\overrightarrow{OH}\cdot\overrightarrow{AB}[/imath]. The problem could definitely have been written to say more clearly what you are expected to do, considering how many things one can try.For question 3 b) how do I find the value of k after I found OH
and I have the same problem for 3d) as well, I don't know what to do to find m and n