How to prove the equality of triangles?

We know three signs of equality of triangles.
1) Two sides of one triangle and the angle between them must be equal to two sides and the angle between them of another triangle. 2) The side and the adjacent corners of one triangle correspond to the side and the adjacent corners of the other triangle. 3) Three sides of one triangle are equal to three sides of another triangle.
In order to prove all these equalities, it is necessary to know what the sides and angles of the triangles are equal to.

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