Question

A triangle is rotated 90° about the origin. Which rule describes the transformation?

A. (x, y) - (x, y)
B. (x, y) - (y, x)
C. (x, y) = (-y, x)
D. (x, y) - (-x, y)

Answer 1

The correct rule that describes a 90° rotation of a triangle about the origin is 'C. (x, y) = (-y, x)'. This is a common transformation in Mathematics dealing with coordinate systems.

Step-by-step explanation:

The student is asking about the rule that describes the transformation of a triangle rotated 90° about the origin in a coordinate system, which falls under the category of transformations in Mathematics. The correct answer to this question is 'C. (x, y) = (-y, x)'.

When a point is rotated 90° clockwise about the origin, the x-coordinate becomes the negative y-coordinate, and the y-coordinate becomes the x-coordinate. This can be seen from trigonometric relationships in rotational transformations, where cos(90°) = 0 and sin(90°) = 1, leading to the transformed coordinates x' = -y and y' = x, which matches option C.