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Reflection Matrix (Posted on 2015-04-01) Difficulty: 3 of 5
⌈1  0⌉⌈x⌉=⌈ x⌉
⌊0 -1⌋⌊y⌋=⌊-y⌋

The above 2x2 matrix reflects a point over the x-axis. (x,y)→(x,-y).

Derive a matrix that will reflect a point over the line y=kx.

No Solution Yet Submitted by Jer    
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Solution researched solution | Comment 1 of 3
[cos(2*atan(k))   sin(2*atan(k))]  
[sin(2*atan(k))  -cos(2*atan(k))]  

based on the Wikipedia article

Ref(theta) = [cos 2*theta   sin 2*theta]
             [sin 2*theta  -cos 2*theta]

But, Jer, I couldn't find anywhere, the codes for the partial square brackets, sometimes used for floor and ceiling.

PS: Well I now found the codes, but they don't seem to be recognized in the "View Source" view, when going back to the regular view. (&bracketlefttp; etc.)

Edited on April 1, 2015, 4:18 pm
  Posted by Charlie on 2015-04-01 16:10:17

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