Hi,
Sum of angles of a triangle is 180 degrees
So, a+c+e = 180
and b+d+f = 180
So, a + b + c + d + e + f = 360
Hence, D
Geometry - Lines & Angles
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Frankenstein
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Frankenstein
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Can you name the source?dell2 wrote:OA is something elseits not D
OA:[spoiler]A=180[/spoiler]
Last edited by Frankenstein on Thu Jun 23, 2011 2:05 am, edited 1 time in total.
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Perhaps the OA is 180 because the intention was to reproduce Q10 in the Diagnostic Test in the OG12:
In the star figure above, we're asked to find the sum of the angles measurements of the 5 points of the star.
An easy approach is to plug in for the angle measurements.
The key is to plug in values that follow the rules of geometry:
Let's start with the most unusual shape, the pentagon inside the star. For any polygon with n sides, the sum of the interior angles = (n-2)*180. Thus, the sum of the angles inside the pentagon = (5-2)*180 = 540. There are 5 angles inside the pentagon. To make the math easy, let's plug in 540/5 = 108 for each interior angle.
Each of the adjacent angles must be 180-108 = 72 (see the picture), because the sum of angles that form a straight line must be 180.
There are 5 triangles around the outside of the star. The sum of the angles inside each of these triangles must be 180. This forces each point of the star to be 180-72-72 = 36.
Since the star has 5 points, the sum of the angle measurements of all 5 points is 5*36 = 180.
In the star figure above, we're asked to find the sum of the angles measurements of the 5 points of the star.
An easy approach is to plug in for the angle measurements.
The key is to plug in values that follow the rules of geometry:
Let's start with the most unusual shape, the pentagon inside the star. For any polygon with n sides, the sum of the interior angles = (n-2)*180. Thus, the sum of the angles inside the pentagon = (5-2)*180 = 540. There are 5 angles inside the pentagon. To make the math easy, let's plug in 540/5 = 108 for each interior angle.
Each of the adjacent angles must be 180-108 = 72 (see the picture), because the sum of angles that form a straight line must be 180.
There are 5 triangles around the outside of the star. The sum of the angles inside each of these triangles must be 180. This forces each point of the star to be 180-72-72 = 36.
Since the star has 5 points, the sum of the angle measurements of all 5 points is 5*36 = 180.
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amit2k9
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yupps different answers for different questions here.
a+...+f = 180+180 = 360
a+...+f = 180+180 = 360
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winniethepooh
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Thanks Mitch you are Great Tutor man awesome job
winniethepooh : OA in my book is 180. i thought answer might be wrong but GMATGuRuNY Proved me wrong.all questions are in 700-800 range, so i think 360 will be too easy answer for such high level scores
winniethepooh : OA in my book is 180. i thought answer might be wrong but GMATGuRuNY Proved me wrong.all questions are in 700-800 range, so i think 360 will be too easy answer for such high level scores
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Thanks, dell2. Just to be clear: the figure shown in your post is different from that shown in mine and in the OG12. Given your figure (in which the center of the star is a hexagon), the sum of the degree measurements of all the points of the star is 360. Given the figure in the OG12 (in which the center of the star is a pentagon), the sum of the degree measurements of all the points of the star is 180. The question in the OG12 is trickier.dell2 wrote:Thanks Mitch you are Great Tutor man awesome job
winniethepooh : OA in my book is 180. i thought answer might be wrong but GMATGuRuNY Proved me wrong.all questions are in 700-800 range, so i think 360 will be too easy answer for such high level scores
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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
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