Question

Triangle A is being rotated 90 degrees counter clockwise. Determine which triangle, would be the image of triangle A after the rotation II II IV

Answer 1

You know that the rotation of a point in the plane 90 degrees counterclockwise is given by

`(x,y)\rightarrow(-y,x)`

So, iIf triangle A has as coordinates

`\begin{gathered} (-2,2), \\ (-6,8)\text{ and} \\ (-10,2) \end{gathered}`

Its rotation 90 degrees counterclockwise, will have the coordinates

`\begin{gathered} (-2,2)\rightarrow(-2,-2) \\ (-6,8)\rightarrow(-8,-6) \\ (-10,2)\rightarrow(-2,-10) \end{gathered}`

Which correspond to triangle D in quadrant III.