We can find this observation in Geometry Strategic guide.
If 2 similar triangles have corresponding side lengths in the ratio a:b then their areas will be in the ratio a2:b2.
I am clear till this place. There is an additional statement mentioned here.
The lengths being compared do not have to the sides. They can represent heights or perimeters. Does it mean that if 2 triangles are similar, their heights will be proportional and their area will be in the ratio of the square of the heights of the triangle?