What are the angles
1.
2.
3.
What are the sides
1.
2.
3.

Step-by-step explanation:

by inspection of the ratio of angles, that's, 1:2:3, we can conclude, it is a right angle.

(30°,60°,90°).

It is a special right triangle. One set square in the geometry box is made of those angles. It's sides are in the ratio of 1:√3:2. Notice the hypotenuse is double the shortest leg. The longer leg is √3 of the shortest leg. If the measurement of one of it's side is known, the lengths of other sides can be calculated from the ratio. Normally, in the same set square, there is a smaller triangle, a cut out portion. They both are similar triangles; as equiangular triangles AAA. All 1:2:3 triangles are similar triangles.

Algebraically, x+2x+3x = 180°; 6=180°; so, x = 30°.