Answer:
D
Explanation:
If two secants intersect to form the vertex of an angle outside a circle and the sides of the angle intercept arcs on the circle, then the measure of the angle is equal to one-half the difference of the measures of the arcs intercepted by the sides of the angle.
So
![85-25=60](https://img.qammunity.org/2020/formulas/mathematics/middle-school/o6wx1geq40fafj3m9veko0kr9ffmdlkb0h.png)
![(60)/(2)=30](https://img.qammunity.org/2020/formulas/mathematics/high-school/nuidbundf2ly7glhhqna72jhnjb1rt3pw3.png)