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I need help on this question

I need help on this question-example-1
User Wycleffsean
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2 Answers

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The answer is C. rotation of 180 around the origin
User Raigex
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Answer:

C) rotation 180° about the origin

Explanation:

Rotation by 90° or 270° will move a figure from one quadrant to an adjacent quadrant. Your figure has moved to the opposite quadrant, so its rotation must be 180°.

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You have probably seen the transformations ...

(x, y) ⇒ (-y, x) . . . . . rotation 90° CCW or 270° CW

(x, y) ⇒ (-x, -y) . . . . . rotation 180°

(x, y) ⇒ (y, -x) . . . . . . rotation 90° CW or 270° CCW

For rotations through other angles, the relation is ...

(x, y) ⇒ (x·cos(θ)-y·sin(θ), x·sin(θ)+y·cos(θ)) . . . . rotation CCW by angle θ

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If you compare the above transformations to the given pairs of coordinates, you see the coordinates correspond to rotation by 180°. (Both x- and y-values are negated, but not swapped.)

User Charles Ofria
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