Rational numbers can be written as a fraction
can be terminating or repeating decimal (terminating means a decimal that stops ex 5.873)
so 50.1 repeating is a rational number
In the given quadrilateral ABCD,


(Sum of interior angles of a quadrilateral is 360 degrees)
(Substitution Property)
(Addition Property of Equality)

60 seconds in a minute
18X60 = 1080
The perimeter of ABCD is 10, therefore, AB+AD=half of 10=5
the perimeter of ABD is 8, therefore, BD=ABD-(AB+AD)=8-5=3
3cm is the answer.