If a triangle and a square are on the same base and between the same parallels, then the ratio of area of triangle to the area of square is
1 : 2
We know that if a triangle and a parallelogram are on the same base and between the same parallels, then the area of the triangle is equal to half the area of the parallelogram.
A square is a parallelogram.
Therefore, required ratio = 1 : 2