Question

Jerome drew a triangle with vertices s, t and u how can Jerome show that the angels are congruent without measuring angles

Answer 1

An angle with all equal angles is called an equilateral triangle, and another property of equilateral triangles is that all of their sides are the same measure.
So, Jerome could measure all the sides of the triangle and prove that all the angles are equal because of the above statement.
Good luck, and I hope I helped!