Hi there!
There are 5 ways to find if two triangles are congruent :
SSS, SAS, ASA, AAS & HL
<u>1. SSS (Side, Side, Side)</u>
Means that we have two triangles with 3 sides equal.
⇒ If 3 sides of one triangle are equal to 3 sides of another triangle, the triangles are congruent.
<u>2. SAS (Side, Angle, Side)</u>
Means that we have two triangles where we know 2 sides and the included angle are equal.
⇒ If 2 sides and the includent angle of one triangle are equal to the corresponding sides and angle of another triangle, the triangles are congruent.
<u>3. ASA (Angle, Side, Angle)</u>
Means that we have two triangles where we know 2 angles and the included side are equal.
⇒ If 2 angles and the included side of one triangle are equal to the corresponding angles and side of another triangle, the triangles are congruent.
<u>4. AAS (Angle, Angle, Side)</u>
Means thant we have two triangles where we know 2 angles and the non-included side are equal.
⇒ If 2 angles and the non-included side of one triangle are equal to the coresponding angles and side of another triangle, the triangles are congruent.
<u>5. HL (Hypotenuse, leg)</u>
** This one only applies to <em><u>right-angled triangles</u></em>.**
Hypotenuse: The longest side of a right-angled triangle.
Legs: The other 2 sides of the right-angled triangle.
Means we have two right-angled triangles with the same length of hypotenuse and the same length for one of the other 2 legs (it doesn't matter which leg since the triangles could be rotated).
⇒ If the hypotenuse and one leg of one right-angled triangles are equal to the corresponding hypotenuse and leg of another right-angled triangles, the two triangles are congruent.
There you go! I really hope this helped, if there's anything just let me know! :)