Originally Posted by

**mathguy80** Hi,

This is a rotation transform problem, that I am struggling with.

The vertices of Triangle ABC are A(1,1), B(2, 2), and C(0,3). The vertices of Triangle A1B1C1 are A1(-2, 2), B1(-3,3), and C1(-4, 1). Describe fully the single transformation which maps Triangle ABC onto A1B1C1.

I can make out that it is a rotation of 90 degrees anti-clockwise. But what is the center of the rotation. How do you find the center of rotation for such transformations where the center is not origin. Thanks for your help!

P.S. Ignore the small letters, haven't figured out how to hide those yet!