Ab is tangent to circle o at b. what is the length of the radius r? round to the nearest tenth. 7.0 3.6 13.0 9.9

In the field of thermodynamics, rankine is the unit used to measure temperature. one can convert temperature from celsius into rankine using the formula c= r/1.8 - 273, what is the temperature in celcius corresponding to r degrees rankine.

Ineed in figuring out this problem.

1) what is the measure of the exterior angle, ∠uvw ? 2) in triangle man, what is the measure of the exterior angle at n (in degrees)?