Answer :

41º

1) Since we want to find the reference angle for a -139º angle, we need to resort to the following formula

[tex]Reference\:Angle\:\:Quadrant\:III=180^{\circ}-139^{\circ}=41^{\circ}[/tex]

2) Note that a -139 angle is in quadrant III, since negative angles are clockwise oriented

3) Thus the Reference Angle is 41º

Answer:

41°

Step-by-step explanation:

Find the acute angle in the first quadrant used as a reference for

−139°.

41°