we know that
The measurement of the exterior angle is the semi-difference of the arcs which comprises
In this problem
∠FGH is the exterior angle
∠FGH=

∠FGH=
-----> equation A

--------> equation B
Substitute equation B in equation A
![100\°=(arc\ FEH-[360\°-arc\ FEH])](https://img.qammunity.org/2018/formulas/mathematics/high-school/29gaxif90k7ufbvb5ssejijcdqlfdk7nip.png)



therefore
The answer is
The measure of arc FEH is equal to
