Question

THoIn the accompanying drawing, ABC is right triangleWhich diagram below shows the image of triangle ABC when rotated 90 counterclockwise about the origin?a133

Answer 1

A counterclockwise rotation changes the coordinate of a point as,

(x,y)-->(-y, x).

So, the x coordinate becomes negative of y coordinate and the y coordinate becomes x after transformation.

Let (x,y) be the coordinates of B. Initially the vertex B is in first quadrant with positive coordinates (x,y).

The transformation will give a negative value for the new x coordinate of B only in the first transformation

Hence, the first figure is the answer.