Question

Rotate ACAT 90° with C(9,0), A(2, -1), and T(-1, 10) about the origin.

Answer 1

A counter clockwise rotation is given by:

`\begin{gathered} x^(\prime)=x\cos (\theta)-y\sin (\theta) \\ y^(\prime)=x\sin (\theta)+y\cos (\theta) \end{gathered}`

For a rotation of 90 degrees:

`\begin{gathered} x^(\prime)=-y \\ y^(\prime)=x \end{gathered}`

Therefore:

`\begin{gathered} A(2,-1)->(-y,x)->A^(\prime)(1,2) \\ C(9,0)->(-y,x)->C^(\prime)(0,9) \\ T(-1,10)->(-y,x)->T^(\prime)(-10,-1) \end{gathered}`