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Hi Bunuel,

Thanks for all that you do. Your explanations have made the study grind a lot more manageable.

I was under the impression that when you write out an angle expression (ex. ∠ABC), it means the angle is formed by the intersection of line AB with line BC (see attached illustration)

Is this the case? If so, I'm having trouble visualizing how you could form the parallelogram above using the given information. Thanks in advance!
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Can someone explain how B can be the vertex of angle CBD if the prompt states AB=CD and AD=BC? I can't figure out how to draw this...
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Hi Bunnel,


Can you please elaborate more on solution .. i got this question wrong.
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Question didn't mentioned that Opposite sides are parallel !!!!

can we still assume that given quadrilateral is Parallelogram?

Requesting expert analysis on this !!!

Thanks in advance

Narayana Raju
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gvvsnraju@1
Question didn't mentioned that Opposite sides are parallel !!!!

can we still assume that given quadrilateral is Parallelogram?

Requesting expert analysis on this !!!

Thanks in advance

Narayana Raju

This is explained in the solution:
Because \(AB = CD\) and \(BC = AD\), \(ABCD\) is a parallelogram.

If two pairs of opposite sides of a quadrilateral are equal in length then the quadrilateral is a parallelogram.
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Bunuel
In quadrilateral \(ABCD\), \(AB = CD\) and \(BC = AD\). If \(\angle CBD = 30\) degrees and \(\angle BAD = 80\) degrees, what is the value of \(\angle ADC\)?

A. 30 degrees
B. 50 degrees
C. 70 degrees
D. 100 degrees
E. 120 degrees

Consecutive angles are supplementary => \(\angle BAD + \angle ADC=180\)

\(\angle ADC=180-80=100\)

Am I right here?
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Here is the image for visual view
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Bunuel
In quadrilateral \(ABCD\), \(AB = CD\) and \(BC = AD\). If \(\angle CBD = 30\) degrees and \(\angle BAD = 80\) degrees, what is the value of \(\angle ADC\)?

A. 30 degrees
B. 50 degrees
C. 70 degrees
D. 100 degrees
E. 120 degrees

Consecutive angles are supplementary => \(\angle BAD + \angle ADC=180\)

\(\angle ADC=180-80=100\)

Am I right here?

Yes, consecutive angles in a parallelogram are supplementary, add to 180°, so yes you are right.
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+1 for option D. The angle is 100.
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Does the position of A, B , C and D matter for these types of problems? If we wanted to draw it, what is the correct placement?
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Does the position of A, B , C and D matter for these types of problems? If we wanted to draw it, what is the correct placement?

OFFICIAL GUIDE:

Problem Solving
Figures: All figures accompanying problem solving questions are intended to provide information useful in solving the problems. Figures are drawn as accurately as possible. Exceptions will be clearly noted. Lines shown as straight are straight, and lines that appear jagged are also straight. The positions of points, angles, regions, etc., exist in the order shown, and angle measures are greater than zero. All figures lie in a plane unless otherwise indicated.

Data Sufficiency:
Figures:
• Figures conform to the information given in the question, but will not necessarily conform to the additional information given in statements (1) and (2).
• Lines shown as straight are straight, and lines that appear jagged are also straight.
• The positions of points, angles, regions, etc., exist in the order shown, and angle measures are greater than zero.
• All figures lie in a plane unless otherwise indicated.
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Because you know that its a parallelogram, you don't need the information that CBD is 30 degrees. Opposite angles in parallelogram are the same and quadrilateral has 360 degrees in total -> ADC = [360-(2*80)]/2
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