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Mathematics 7 Online
OpenStudy (cloverracer):

Geometry question. Please see attachment

OpenStudy (cloverracer):

OpenStudy (cloverracer):

@TheSmartOne

TheSmartOne (thesmartone):

umm. I don't know how to explain it.

OpenStudy (mathstudent55):

Look at triangle BDC. It has a 34-deg angle.

OpenStudy (mathstudent55):

|dw:1418942246559:dw|

OpenStudy (cloverracer):

Yes I see.

TheSmartOne (thesmartone):

well the larger the angle the longer the lenght should be.

OpenStudy (mathstudent55):

Now using the common side, BD, and the congruent sides, BC and AB, think of drawing this on a piece of paper, then fold the paper along line BD.

TheSmartOne (thesmartone):

|dw:1418942412934:dw|

OpenStudy (cloverracer):

Quick question, would you use the converse of the hinge theorem?

OpenStudy (mathstudent55):

|dw:1418942399533:dw|

OpenStudy (mathstudent55):

Since AD is only 22, which is less than 30, when you fold triangle ABD over along line BD, side AD is only 22, so point A cannot reach point C, and falls on side DC as shown in figure above.

OpenStudy (cloverracer):

Oh okay I see

OpenStudy (mathstudent55):

Now notice that in this new position, side AD is smaller than side DC. That means the oposite angle to side AD must be smaller that the opposite angle to side DC.

OpenStudy (mathstudent55):

Since angle DBC is 34, angle ABD must be less than 34. Both angles must be greater than 0 since they are angles of a triangle.

OpenStudy (cloverracer):

So it would be somewhat like this I guess?.. ABD >34

OpenStudy (mathstudent55):

Therefore, you can write: \(0^o \lt m\angle ABD \lt 34^o \) but since \(m\angle ABD = 2x\), You can write: \(0^o \lt 2x \lt 34^o\)

OpenStudy (cloverracer):

ohhh okay!

OpenStudy (mathstudent55):

Now divide both sides by 2 to get: \(0^o \lt x \lt 17^o\) The range of x is between 0 and 17 degrees.

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