Answer:
Perpendicular bisector theorem
Step-by-step explanation:
The illustration of the theorem is:
If point B is a perpendicular bisector of Line AC and the length of AC is 10cm
Then

Where
--- Perpendicular bisector
So, the equation becomes



Recall: 

Answer:
Step-by-step explanation:
sales tax on the shirt= 20(0.09)=1.8 dollars
total cost with sales tax =20+20(0.09)=21.8$
it would equal the same mixed number. 5 2/3