# Two Math Questions.

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• Nov 6th 2008, 10:53 AM
dgenerationx2
Two Math Questions.
1. (-2, 2) reflected through the origin is:

A. (2, 2)
B. (2, -2)
C. (-2, 2)
D. (-2, -2)

20. A picture measures 16 inches wide by 20 inches long. If the frame is to be 20 inches wide. What is the scale factor of the frame as a dilation of the picture, and what is the length of the frame?

A. scale factor is 5/4, length of frame is 25 inches
B. scale factor is 4/5, length of frame is 16 inches
C. scale factor is 1/1, length of frame is 16 inches
D. scale factor is 4/1, length of frame is 24 inches
• Nov 6th 2008, 11:39 AM
masters
Quote:

Originally Posted by dgenerationx2
1. (-2, 2) reflected through the origin is:

A. (2, 2)
B. (2, -2)
C. (-2, 2)
D. (-2, -2)

Try graphing the point. (-2, 2) is 2 units left of the origin and 2 units up. Its reflection will be 2 units right of the origin and 2 units down.
Quote:

Originally Posted by dgenerationx2
20. A picture measures 16 inches wide by 20 inches long. If the frame is to be 20 inches wide. What is the scale factor of the frame as a dilation of the picture, and what is the length of the frame?

A. scale factor is 5/4, length of frame is 25 inches
B. scale factor is 4/5, length of frame is 16 inches
C. scale factor is 1/1, length of frame is 16 inches
D. scale factor is 4/1, length of frame is 24 inches

Scale factor (dilation factor) is 16/20 or 4/5. We find this by using the ratio of the two widths.

To find the new length solve this: $\displaystyle \frac{20}{L}=\frac{4}{5}$