1. The sum of the internal angles of the triangle is 180 degrees.

2. An isosceles triangle has equal waists.

An equilateral triangle has three equilateral sides and all three angles are 60 degrees.

4. The midline of the isosceles triangle is parallel to the third side and equal to half of the third side.

The median line on the hypotenuse of a right triangle is half of the hypotenuse.

6. isosceles triangle with three lines in one

I wrote it all myself.