Step by step
The question
Question: which rule shows that triangles ABC and DEF are congruent?
1 Match the parts
Congruent means the same shape and the same size.
One fits exactly on top of the other.
The order of the letters shows which corners match: A with D, B with E, C with F.
DEF is turned over.
That does not matter.
Angle B and angle E are both 55°: a pair of equal angles.
A for angle.
BC and EF are both 8: a pair of equal sides.
S for side.
Angle C and angle F are both 45°: a pair of equal angles.
A for angle.
2 Find the rule
BC is between the two angles: its letters are the two corners, B and C.
Go round: angle, side, angle: A S A.
The two angles fix the shape.
The side between them fixes the size.
There is only one way to draw it.
So A S A shows the triangles are congruent.
Let's look back.
First: match the parts.
Last: find the rule.