|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
03 Mar 2019, 13:55
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
59% (02:25) correct
41%
(02:39)
wrong
based on 68
sessions
History
Date
Time
Result
Not Attempted Yet
GMATH practice exercise (Quant Class 1)
If line AC bisects angle BCD, what is the measure of angle ADC?
(A) 20 degrees
(B) 30 degrees
(C) 40 degrees
(D) 45 degrees
(E) 50 degrees
If line AC bisects angle BCD, what is the measure of angle ADC?
(A) 20 degrees
(B) 30 degrees
(C) 40 degrees
(D) 45 degrees
(E) 50 degrees
03 Mar 2019, 14:49
Kudos
Bookmarks
Lots of good lines/angles and triangles rules to refresh for this one:
-When two parallel lines are cut by a transversal, corresponding angles are equal
-Vertical angles are equal
-Supplemental angles sum to 180 degrees
-All the angles around one point sum to 360 degrees
-All three angles in a Triangle sum to 180 degrees
If you know all those rules and are comfortable with "extending lines," then this question isn't too challenging.
-When two parallel lines are cut by a transversal, corresponding angles are equal
-Vertical angles are equal
-Supplemental angles sum to 180 degrees
-All the angles around one point sum to 360 degrees
-All three angles in a Triangle sum to 180 degrees
If you know all those rules and are comfortable with "extending lines," then this question isn't too challenging.
Attachments
IMG_2684.jpg [ 1.26 MiB | Viewed 4443 times ]
03 Mar 2019, 15:00
Kudos
Bookmarks
fskilnik
All angles are measured in degrees.
\(? = x\)
\(\left( 1 \right)\,\,{\text{angle}}\,\,DCE\,\,\, = \,\,\,20 + x\,\,\,\,\,\,\left[ {\,{\text{exterior}}\,\,{\text{angle}}\,\,{\text{of}}\,\,\Delta ADC\,} \right]\)
\(\left( 2 \right)\,\,{\text{angle}}\,\,ECB\,\,\, = \,\,\,20 + x\,\,\,\,\,\,\left[ {\,{\text{line}}\,\,AC\,\,{\text{bisects}}\,\,\,{\text{angle}}\,\,BCD\,} \right]\)
\(\left( 3 \right)\,\,{\text{angle}}\,\,DAC\,\,\, = \,\,\,{\text{angle}}\,\,AEB\,\,\, = \,\,\,20\,\,\,\,\,\,\left[ {\,{\text{lines}}\,\,AD\,\,{\text{and}}\,\,BE\,\,{\text{are}}\,\,{\text{parallel}}\,} \right]\)
\(\Delta BCE\,\,:\,\,\,20 + x = 180 - \left( {110 + 20} \right)\,\,\,\,\, \Rightarrow \,\,\,\,\,? = x = 30\)
The correct answer is (B).
We follow the notations and rationale taught in the GMATH method.
Regards,
Fabio.
