Answer:
The length of the unknown side x is 4 cm
Step-by-step explanation:
we know that
The perimeter of a polygon is equal to the sum of its length sides
Remember that
1 cm=10 mm
In this problem we have
AB=45 mm ------> convert to cm -----> AB=45/10=4.5 cm
BC=10 cm 4 mm -----> convert to cm -----> BC=10+4/10=10.4 cm
CD=5 cm 6 mm -----> convert to cm -----> CD=5+6/10=5.6 cm
DE=35 mm ------> convert to cm -----> DE=35/10=3.5 cm
EA=x cm
P=280 mm ------> convert to cm -----> P=280/10=28 cm
The perimeter of the irregular polygon is equal to
P=AB+BC+CD+DE+EA
substitute the values
28=4.5+10.4+5.6+3.5+x
28=24+x
x=28-24
x=4 cm
