Question

prove that the rotation about +90° with centre origin followed by ratation about 180° is the reflection about y-axis by calculating 2*2 matrix​

Answer 1

Step-by-step explanation:

Let's study an example problem

We want to find the image A'A

′

A, prime of the point A(3,4)A(3,4)A, left parenthesis, 3, comma, 4, right parenthesis under a rotation by 90^\circ90

∘

90, degrees about the origin.

Let's start by visualizing the problem. Positive rotations are counterclockwise, so our rotation will look something like this:

Cool, we estimated A'A

′

A, prime visually. But now we need to find exact coordinates. There are two ways to do this.