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Re: In the figure above, if z = 50, then x + y = [#permalink]

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18 Jun 2013, 23:50

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My 30 second solution:

sum of angles in triangle = 180

Sum of angles in small triangle: (180-y) + (180-x) + 90 = 180 --> x+y = 270

IMO the information z = 50 is not needed to calculate x+y if we know that the two vertical lines are parallel and hence we have a right angle in the smaller triangle. Let me know if my reasoning is wrong.

Re: In the figure above, if z = 50, then x + y = [#permalink]

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19 Jun 2013, 02:18

1

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kingflo wrote:

My 30 second solution:

sum of angles in triangle = 180

Sum of angles in small triangle: (180-y) + (180-x) + 90 = 180 --> x+y = 270

IMO the information z = 50 is not needed to calculate x+y if we know that the two vertical lines are parallel and hence we have a right angle in the smaller triangle. Let me know if my reasoning is wrong.

Cheers

An exterior angle of a triangle ( In this case y) is always equal to the sum of the opposite interior angles [ In this case 90 degrees and (180-x)]

Re: In the figure above, if z = 50, then x + y = [#permalink]

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29 Nov 2013, 13:17

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Yes, the setup of y = 90 + (180 - x)

is a great way to solve this question without knowing x or y.

If you are not familiar with spotting exterior angles and prefer to do things the old school way - well, there's plenty of information in the diagram from which you can gather together to find the actual value of y. And then from there you can solve for x and then add up x and y.

Either method works fine.

Below is a video demonstration of the adding up x and y approach:

Re: In the figure above, if z = 50, then x + y = [#permalink]

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25 Jul 2014, 00:06

I think I don't understand an important part in this question here.. What is meant by x + y ? I thought it is the value of the angles? (blue + red one)

So i would have calculated 40 + 130. Can anyone help me ?

I think I don't understand an important part in this question here.. What is meant by x + y ? I thought it is the value of the angles? (blue + red one)

So i would have calculated 40 + 130. Can anyone help me ?

Yes, the question asks about the sum of the measures of angles x and y. x = 140° and y = 130°, so the sum is 270°.

In the figure above, if z = 50, then x + y = [#permalink]

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05 Nov 2015, 05:35

x + y = 360 - 90 (the right angle of the smaller triangle, which equals the other two angles of the smaller triangle). We don't need z to compute it
_________________

When looking at the diagram, we want to start with the quadrilateral that contains angles z and y. We must remember that any quadrilateral has a total of 360 degrees. We know that two angles of the given quadrilateral are 90 degrees each and that z = 50 degrees. Thus, we can set up the following equation to determine the measure of angle y.

90 + 90 + 50 + y = 360

230 + y = 360

y = 130

Now that we know the value of angle y, we can move to the triangle in the lower part of the diagram. Let’s label it triangle ABC and draw it below. We see that angle ACB and angle y are supplementary, so angle ACB = 180 – 130 = 50 degrees. We also see that the triangle is a right triangle so the remaining angle, angle ABC = 180 – (90 + 50) = 40 degrees. Finally, since angle ABC and angle x are supplementary we see that angle x = 180 – 40 = 140 degrees.

Thus, x + y = 140 + 130 = 270.

The answer is D.
_________________

Jeffery Miller Head of GMAT Instruction

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