The ratio of the angles of a triangle is equal to the ratio of the numbers 1, 2, and 3. Prove that it is a right-angled triangle.

the sum of all the angles of a triangle is 180 degrees
Let x be the ratio of the angles, then we get
180 degrees = x + 2 * x + 3 * x = 3 * x + 3 * x = 6 * x
6 * x = 180 degrees
x = 180/6 degrees
x = 30 degrees
2 x = 60 degrees
3 x = 90 degrees
from here it can be seen that the triangle has a right-angled right angle equal to 90 degrees.
then the triangle is rectangular.