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parallel lines.

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by kanha81 » Mon Jun 08, 2009 6:45 am
From the attached figure, find the angle ACD.

A. 100
B. 90
C. 80
D. 70
E. cannot be determined from the information

I got this answer right, but did some calculations. I also found a much simpler way to determine the answer in much simpler way :)
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Source: — Problem Solving |

by tohellandback » Mon Jun 08, 2009 6:51 am
IMO 80

join DC with AB. joining angle will be 50 because lines are parallel.

see the attachment
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by tompal » Mon Jun 08, 2009 7:57 am
I’m also getting 80º, but my approach was a bit different… please let me know if my thinking is correct…

Since AB||DE a straight line can be drawn form point A to Point D that would be perpendicular. With the resulting 90º angels you can calculate the interior angles of triangle ACD then subtract to get the measure of angle C, see the illustration…

What is the OE
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