Value of angle x

This topic has expert replies
Source: — Problem Solving |

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Fri Mar 11, 2016 2:14 am
What is the value of x?

a)105
b)130
c)135
d)140
e)145
Image
An inscribed angle is formed by 2 chords.
Since ∠AED is formed by chords AE and DE, ∠AED is an inscribed angle.
Chords AE and ED intercept arc ABCD on the circle.
The degree measurement of an inscribed angle is equal to 1/2 the degree measurement of the intercepted arc.
Since ∠AED = 75º, arc ABCD = 150º.


Image
Since AB=BC=CD, arc AB = arc BC = arc CD.
Since arcs AB, BC and CD together constitute 150º of the circle, arc AB = 50º, arc BC = 50º, and arc CD = 50º.


Image
Since arc BC + arc CD = 50+50 = 100º, arc BAED = 360-100 = 260º.
Arc BAED is intercepted by inscribed angle x.
Since the degree measurement of an inscribed angle is 1/2 the degree measurement of the intercepted arc, x = (1/2)(260) = 130.

The correct answer is B.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

Senior | Next Rank: 100 Posts
Posts: 67
Joined: Sat Jun 21, 2014 10:31 pm
Followed by:1 members

by binaras » Fri Mar 11, 2016 9:58 pm
Hi Mitch,


Thanks so much for this explanation.

Binara