Thread: Rotation matrix

Hi Guys and Girls,

I have the following problem and have no idea about where to start.

Give an example of a 2 by 2 rotation matrix that rotates the point
( 7 , 7 )
into the square with corners
( -1 , -10 )
( 1 , -10 )
( 1 , -8 )
( -1 , -8 )



I have a feeling that I would need to use the rotation matrix

Cos(x) -Sin(x)
Sin(x) Cos(x)

But am confused as to what the points would be.


Thanks

KJx



n

Hey KingJohnno.

Hint: Try expanding out your linear system to get solutions in terms of sin(x) and cos(x) and then find x with respect to the right quadrant using arc-cos and arc-sin.

Here's a solution and a general rotation matrix for such problems:

Brilliant - Thanks for your help John. (we share the same initials!) I sort of understand what is going on now, I emailed my tutor and he went through it with me! Thank you :-)