Question

The vertices of a trapezoid are `A(1, 1), B(2, 2), C(4, 2),` and `D(5, 1)`. If you rotate the trapezoid 90° clockwise about the origin, what are the new coordinates?

Answer 1

`A' = (1, -1)`
`B' = (2, -2)`
`C' = (2, -4)`
`D' = (1, -5)`

Explanation:

This clockwise rotation is equivalent to a reflection in the `45^@` line `y = x`, followed by a reflection in the `x` axis.

That is, it is equivalent to swapping the `x` and `y` coordinates, then inverting the sign of the `y` coordinate.