Question

A point at (−1, 10) is rotated 90°counterclockwise about the origin. What are the coordinates of the resulting image?

A (−1, −10)
B (−10, −1)
C (10, 1)
D (1, −10)

Answer 1

The answer should be B

Answer 2

The resulting image of given point is (-10,-1)

B is correct.

Explanation:

A point at (−1, 10) is rotated 90°counterclockwise about the origin.

Rotation about origin counterclockwise. (Using the rule)

`R_(90^\circ)(x,y)\rightarrow (-y,x)`

The x coordinate of image point is negative of y value of given point.

The y-coordinate of image point is x coordinate of given point.

`(-1,10)\rightarrow (-10,-1)`

-1 changes to -10

10 changes to -1

Hence, The resulting image of given point is (-10,-1)