Vectors Q (1 Viewer)

dsakvyilsa

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Hey, just need some help understanding the worked solution for this question. Thanks! (first image is Q, second is worked solution)20230125_101211.jpg20230125_101218.jpg
 

dsakvyilsa

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the part that throws me off is the line where |b|^2 comes in, I can understand how they used it to get the solution but I don't understand where it actually came from.
 

Masaken

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the part that throws me off is the line where |b|^2 comes in, I can understand how they used it to get the solution but I don't understand where it actually came from.
b.b = |b|^2
they're expanding it out but subbing that identity immediately
 

5uckerberg

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I believe that in my memory this is where it comes from
.
This comes from the angle for vectors.
There, what you do is replace with and then what you will have is
.
The interesting part is that since lies in the same direction of then which leads to beccause . Note this is for two vectors going in the same direction.
For vectors going in the opposite direction
.

Vectors in this case are parallel and collinear.
 
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dsakvyilsa

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b.b = |b|^2
they're expanding it out but subbing that identity immediately
wait omg I didn't even notice that the brackets had two b's 🤦🏼‍♀️ I thought they were 4 different terms for some reason ☠ damn
 

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