# Thread: triangle divided into isosceles triangles

1. ## triangle divided into isosceles triangles

Hi, can any triangle be divided into isosceles triangles? How to prove or disprove that? Thanks a lot.

2. Hello,
Originally Posted by disclaimer
Hi, can any triangle be divided into isosceles triangles? How to prove or disprove that? Thanks a lot.
What do you think about considering the circumscribed circle ?

Let ABC be the triangle and O be the center of this circle.
OA=OB=OC.

So it may be interesting to see the properties of triangles OAB, OAC and OBC

3. Ah, right, silly me.

Moo, I see that you've posted A LOT since my last visit here.

Thanks.

4. Originally Posted by disclaimer
Hi, can any triangle be divided into isosceles triangles? How to prove or disprove that? Thanks a lot.
In my opinion this is only possible if the triangle doesn't contain an obtuse interior angle.

Then the center of the circumscribed circle is outside the triangle and at least 2 of the radii are placed outside the triangle too.

5. Originally Posted by earboth
In my opinion this is only possible if the triangle doesn't contain an obtuse interior angle.

Then the center of the circumscribed circle is outside the triangle and at least 2 of the radii are placed outside the triangle too.
I see your point here. But still, maybe there's a different way of proving that property for an obtuse-angled triangle?

6. LoL, I think I got it.

You can always inscribe a circle in a triangle. Then, connecting the points of tangency with the sides of the triangle to the center of the circle and drawing another triangle whose vertices are also those tangency points, we obtain six isosceles triangles within the original one.

Don't you guys think so?

7. Originally Posted by disclaimer
LoL, I think I got it.

You can always inscribe a circle in a triangle. Then, connecting the points of tangency with the sides of the triangle to the center of the circle and drawing another triangle whose vertices are also those tangency points, we obtain six isosceles triangles within the original one.

Don't you guys think so?
Good spot !