Answer:
[tex]13\pi/2[/tex]
Step-by-step explanation:
The formula of the circumference of a circle is [tex]2\pi r[/tex].
The length of an arch can be found by using the ratio of circumference to the arc.
First, find the circumference of the circle:
[tex]2\pi *13=26\pi[/tex]
Then you find the ratio:
The length of the arc is 90/360, which is 1/4, of the circumference.
Finally, find the length of the arc:
[tex]26\pi*1/4=(13/2)\pi[/tex] or [tex]13\pi/2[/tex]
I hope this helps :)