What is the ordered pair of [tex]\( C^{\prime} \)[/tex] after point [tex]\( C(1,2) \)[/tex] is rotated [tex]\( 90^{\circ} \)[/tex] clockwise?

A. [tex]\( C^{\prime}(-1,2) \)[/tex]
B. [tex]\( C^{\prime}(1,-2) \)[/tex]
C. [tex]\( C^{\prime}(2,1) \)[/tex]
D. [tex]\( C^{\prime}(2,-1) \)[/tex]



Answer :

To determine the coordinates of [tex]\(C'\)[/tex] after rotating point [tex]\(C(1,2)\)[/tex] by [tex]\(90^\circ\)[/tex] clockwise, follow these steps:

1. Understand Rotation Transformation:
The formula for rotating a point [tex]\((x, y)\)[/tex] by [tex]\(90^\circ\)[/tex] clockwise around the origin is:
[tex]\[ (x, y) \rightarrow (y, -x) \][/tex]

2. Apply the Rotation Formula:
- Identify the coordinates of point [tex]\(C\)[/tex], which are [tex]\((1, 2)\)[/tex].
- Substitute [tex]\(x = 1\)[/tex] and [tex]\(y = 2\)[/tex] into the rotation formula:
[tex]\[ (x, y) \rightarrow (y, -x) \rightarrow (2, -1) \][/tex]

3. Determine the New Coordinates:
- After rotating [tex]\(C\)[/tex] by [tex]\(90^\circ\)[/tex] clockwise, the new coordinates [tex]\(C'\)[/tex] are:
[tex]\[ C' = (2, -1) \][/tex]

Thus, the ordered pair of [tex]\(C'\)[/tex] after rotating point [tex]\(C(1,2)\)[/tex] by [tex]\(90^\circ\)[/tex] clockwise is:
[tex]\[ C^{\prime}(2, -1) \][/tex]