Answer:
Label the side opposite to the given vertex in upper case in the same lower case.
Explanation:
Here, each vertex is labelled with a Upper case letter.
We need to label the side opposite to that vertex in the lower case.
1. Consider Δ XYZ
Side opposite to vertex X = Side Z Y
So label side Z Y as x.
Side opposite to vertex Y = Side Z X
So label side Z X as y.
Side opposite to vertex Z = Side X Y
So label side X Y as z.
2. Consider Δ QRS
Side opposite to vertex Q = Side R S
So label side R S as q.
Side opposite to vertex R = Side Q S
So label side Q S as r.
Side opposite to vertex S = Side Q R
So label side Q R as s.
3. Consider Δ DEF
Side opposite to vertex D = Side EF
So label side EF as d.
Side opposite to vertex E = Side D F
So label side DF as e.
Side opposite to vertex F = Side DE
So label side DE as f.
4. Consider Δ SRT
Side opposite to vertex S = Side RT
So label side RT as s.
Side opposite to vertex R = Side ST
So label side ST as r.
Side opposite to vertex T = Side SR
So label side SR as t.