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Mathematics 7 Online
OpenStudy (calculusxy):

geometry question. the figure will be drawn below ...

OpenStudy (calculusxy):

|dw:1443914739956:dw| In the figure above, if z = 30, what is the value of x + y ?

OpenStudy (calculusxy):

I thought that it was 150

OpenStudy (jhannybean):

|dw:1443914836421:dw|

OpenStudy (jhannybean):

So \(\angle z\) is an alternate interior angle to both \(\angle x\) and \(\angle y\) therefore \(\angle z = \angle x =\angle y = 30\)

OpenStudy (calculusxy):

so if z = 30 then wouldn't x equal to 75 or would it be 60?

OpenStudy (jhannybean):

Okay, let's look at it a different way.

OpenStudy (jhannybean):

Let's say that in order to complete all the interior angles of a triangle, it has to be = 180, yes?

OpenStudy (calculusxy):

yes

jimthompson5910 (jim_thompson5910):

hints |dw:1443915336204:dw|

OpenStudy (jhannybean):

Therefore, if we take in to consideration the missing sides, then we will see that (180-y) will make a supplementary angle

OpenStudy (jhannybean):

and the same goes for x. (180 - x) will give you the other missing angle within the triangle

OpenStudy (calculusxy):

@jim_thompson5910 so the triangle is not an equilateral triangles?

OpenStudy (jhannybean):

And then if you add \(\angle z\) + missing side 1 + missing side 2, it would total to 180..

OpenStudy (jhannybean):

An equilateral triangle means that all sides are 60 degrees.

OpenStudy (calculusxy):

oh yeah i completely forgot about that

OpenStudy (calculusxy):

would the answer be 210?

OpenStudy (jhannybean):

missing side 1 = 180 - x missing side 2 = 180 - y we have z. z+ missing side 1 + missing side 2 = 180 z + (180 - x) + (180 - y) = 180

jimthompson5910 (jim_thompson5910):

`so the triangle is not an equilateral triangles?` it's not guaranteed it's equilateral, so it's hard to say if yes or no

OpenStudy (zarkon):

210 is correct

OpenStudy (calculusxy):

thank you!

OpenStudy (jhannybean):

30 + 360 -x-y = 180 x + y = 30 + 360 - 180 = 210

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