What must be true about the width of joel’s compass opening before he draws the arc

The choices can be found elsewhere and as follows:

It must be the same as it was when constructing the arc above P.
It must be wider than it was when constructing the arc above P.
It must be narrower than it was when constructing the arc above P.

I think the correct answer is the first option, It must be the same as it was when constructing the arc above P. The intersections of the arcs above  and below the line are joined to produce the perpendicular bisector.

135  units^2

Step-by-step explanation:

1/2b x h

18/2=9

9* 15= 135

Hope this helps