Frododontgo
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Currently in FP1 we’re learning about reflections in a line through the origin which makes the angle theta with the positive x-axis.

I understand when we translate (1,0), but I’m completely lost when translate (0,1). Could someone help me with the concept?
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Frododontgo
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Here’s what we’re doing and I just don’t understand it
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RDKGames
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(Original post by Frododontgo)
Here’s what we’re doing and I just don’t understand it
Ignoring angles at the moment, can you imagine (0,1) being reflected like indicated in the diagram? Do you agree that its image must be somewhere in the bottom right of the diagram?

Do you also agree that the length of the line from the origin to the image must be 1?
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Frododontgo
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(Original post by RDKGames)
Ignoring angles at the moment, can you imagine (0,1) being reflected like indicated in the diagram? Do you agree that its image must be somewhere in the bottom right of the diagram?

Do you also agree that the length of the line from the origin to the image must be 1?
Yes, I agree with that, but I don't understand how the small triangle is similar to the other two
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RDKGames
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(Original post by Frododontgo)
Yes, I agree with that, but I don't understand how the small triangle is similar to the other two
Not sure what you're referring to here.

But now just put in the angles. We have the \theta, which is fine as this is what was originally there. Now you also need to introduce the angle \phi to make life simple.

Upon observation, it is clear that the image has coordinates (\cos \phi , - \sin \phi).

But now you should be interested in expressing \phi in terms of the original angle \theta.
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