Answer:
I) Eq(1) reason: sum of segments of a straight line
II) Eq(2) reason: Given PQ = ST & PS = RT
III) Eq(3) reason: sum of segments of a straight line
IV) Eq(4) reason: Same value on right hand sides of eq(2) and eq(3) demands that we must equate their respective left hand sides
V) Eq(5) reason: Usage of collection of like terms and subtraction provided this equation.
Step-by-step explanation:
We are given that;
PS = RT and that PQ = ST
Now, we want to prove that QS = RS.
From the diagram, we can see that from concept of sum of segments of a straight line we can deduce that;
PQ + QS = PS - - - - (eq 1)
Now, from earlier we saw that PQ = ST & PS = RT
Thus putting ST for PQ & PS for RT in eq 1,we have;
ST + QS = RT - - - - (eq 2)
Again, from the line diagram, we can see that from concept of sum of segments of a straight line we can deduce that;
RS + ST = RT - - - - -(eq 3)
From eq(2) & eq(3) we can see that both left hand sides is equal to RT.
Thus, we can equate both left hand sides with each other to give;
ST + QS = RS + ST - - - (eq 4)
Subtracting ST from both sides gives;
ST - ST + QS = RS + ST - ST
This gives;
QS = RS - - - - (eq 5)
Thus;
QS = RS
Proved
