The combined triangles will look as shown below:
It can be observed that the lengths of the three sides fit alongside one another perfectly. This means that the lengths are equal.
Also, the middle piece of the three triangles has no space when it aligns with the other two triangles. This means that all the angles add up to 180°.It would also be a safe assumption that the angles are equal to each other, therefore the measure of each angle will be:
Therefore, it can be observed that the sides and angles of the three triangles are equal.