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2000 AMC 12 Problems/Problem 10

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Problem

The point P = (1,2,3) is reflected in the xy-plane, then its image Q is rotated by 180^\circ about the x-axis to produce R, and finally, R is translated by 5 units in the positive-y direction to produce S. What are the coordinates of S?

\text {(A) } (1,7, - 3) \qquad \text {(B) } ( - 1,7, - 3) \qquad \text {(C) } ( - 1, - 2,8) \qquad \text {(D) } ( - 1,3,3) \q...

Solution

Step 1: Reflect in the xy plane. That is the same as creating the additive inverse of z and sticking it into the z coordinate. (1,2,-3)

Step 2: Rotate around x-axis 180 degrees. That is the same as taking the additive inverse of y and sticking it in the y coordinate, then taking the additive inverse of z and sticking it into the z coordinate. (1, -2, 3)

Step 3: Translate 5 units in positive-y direction. That is the same as adding 5 to y and sticking it in the y coordinate. (1,3,3) \Rightarrow \text {(E) }

See Also

2000 AMC 12 (ProblemsResources)
Preceded by
Problem 9
Followed by
Problem 11
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
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