9514 1404 393
Answer:
21.5 cm
Step-by-step explanation:
Consider rectangle PQRS. Its area is ...
A = LW
90 cm² = PQ×QR = PQ×(20 cm)
(90 cm²)/(20 cm) = PQ = 4.5 cm . . . . . . BC has this value, too
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Consider the perimeter of ABCD. It is given by ...
P = 2(L +W)
52 cm = 2(AB +BC) . . . . substitute known value for P
26 cm = AB +4.5 cm . . . . use known value for BC, divide by 2
21.5 cm = AB
