Answer :
PR must be less than 26cm as PQ + QR = 26cm
PR must be more than 16cm as PD- QR = 16cm
At both those limits the sides would lay on top of each other.
PR must be more than 16cm as PD- QR = 16cm
At both those limits the sides would lay on top of each other.
Let
x---------> the possible lengths for PR
we know that
The Triangle Inequality Theorem states that the sum of any 2 sides of a triangle must be greater than the measure of the third side
so
case 1)
[tex] x+5 >21\\ x >16 [/tex]cm
case 2)
[tex] x+21 > 5\\ x >-16 [/tex]cm
case 3)
[tex] 21+5 > x\\ 26 > x\\ x < 26 [/tex]cm
so
[tex] 16 < x < 26 [/tex]
therefore
the answer is
PR must be less than [tex] 26 [/tex]cm and must be more than [tex] 16 [/tex]cm