# Thread: Find unknown angles of a triangle!!!

1. ## Find unknown angles of a triangle!!!

Dear friends,

I am unable to find out the unknown angles for the following triangle which I attached with this post.

Angle BAD and angle BCD are the unknown angles need to be calculated. Given that lines AB=BC=CD and angle CDE = 108 degrees

From my calculations: angle ADC = 180 - 108 = 72 degrees (angles on a straight line)

angle BAD + angle BCD = 108 degrees (exterior angle of a triangle = sum of interior opposite angles)

I could not proceed any further beyond this. I thought line DB (median) is bisecting angle ADC since line DB is bisecting line AC (AB=BC) but this only happens in case of isosceles and equilateral triangles.

I am very much stuck here and seek your kind suggestions here. I am also suspecting something could be wrong in the diagram of the triangle or may be the unknown angles. Let me know where I am wrong. Thanks in advance.

2. Originally Posted by tantrik

Angle BAD and angle BCD are the unknown angles need to be calculated. Given that lines AB=BC=CD and angle CDE = 108 degrees
Are we maybe supposed to assume that angle ACD measures ninety degrees?

3. Originally Posted by stapel
Are we maybe supposed to assume that angle ACD measures ninety degrees?
That is where I am also confused. The diagram provided by the math teacher did not state anything about angle ACD.

4. Originally Posted by tantrik

The diagram provided by the math teacher did not state anything about angle ACD

If the phrase "right triangle" does not appear in any of the materials for this exercise, then you might ask about angle ACD.

In the meantime, you could follow Stapel's suggestion, and set angle ACD to 90 degrees (in order to proceed).

I also note that those stroke marks appearing in segments AB, BC, and CD could denote that those three segments all have the same length. That info might come in handy.

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