A triange can be of any size
In an isosceles triangle, two of the angles are the same.
There is no such thing as a milemeter. Assuming you meas millimetres, there is no answer possible because it will depend on the shape and size of the triangle as well as what characteristic of the triangle is being measured.
If it is an equilateral triangle then it will have 3 equal angles If it is an isosceles triangle then it will have 2 equal angles plus another different size angle
It is 4/9 of the small triangle plus the size of the small triangle
A scalene triangle can be the size of a mosquito or the size of a city. The only thing you know about it is that no two of its sides are equal. If you only know that it's a scalene triangle, then there's no way to know how long any of its sides is.