At 139°, this is an obtuse angle, opened up past a square corner but not yet flat. Its supplement is 41°, so a 139° angle and a 41° angle side by side make a straight line.
139° is 139/360 of a full circle, or 139π/180 radians. If you face north and turn 139° clockwise, you end up facing between SE and SSE (closest to southeast (SE)).
139° angle facts
| Angle type | Obtuse angle (between 90° and 180°) |
|---|---|
| Supplement (adds to 180°) | 41° |
| Explement (adds to 360°) | 221° |
| Radians | 139π/180 ≈ 2.426008 |
| Gradians | 154.4444 grad |
| Fraction of a turn | 139/360 (38.61%) |
| Degrees, minutes, seconds | 139° 0′ 0″ |
| Compass bearing | between SE and SSE (closest to southeast (SE)) |
Trigonometric values of 139°
| Function | Value |
|---|---|
| sin 139° | 0.656059 |
| cos 139° | −0.75471 |
| tan 139° | −0.869287 |
139° on a protractor
How to draw a 139° angle with a protractor
- Draw a straight line with a ruler. This is the first arm; mark the vertex at one end.
- Place the center mark of the protractor exactly on the vertex and line up the 0° baseline with your line.
- Find 139° on the row of numbers that reads 0° on your line (protractors have two rows running in opposite directions) and make a small dot at the edge.
- Remove the protractor and draw a line from the vertex through the dot. Mark the angle with an arc and label it 139°.
Drawing it a 139° angle without a protractor (rise and run method)
- 139° = 180° − 41°. Draw a straight line, pick a vertex on it, and build a 41° angle on one side as follows; the angle on the other side of the new line is 139°.
- Draw a straight baseline and measure exactly 10 inches along it from the vertex.
- At the 10-inch mark, draw a short line straight up at 90° (use a carpenter's square or the corner of a sheet of paper).
- Measure 8.69 inches (about 8 11/16″) up that line and make a mark.
- Join the mark to the vertex. The angle at the vertex is 41°, because tan 41° ≈ 0.8693.
Where you see 139° angles
- The Earth turns 139° on its axis in about 9 h 16 min.
- Obtuse angles like 139° appear in reclining chair backs, open laptop screens, fan blades, and the corners of many-sided polygons.
Related angles
139° angle FAQ
What type of angle is 139°?
A 139° angle is an obtuse angle, because it is between 90° and 180°.
What is the supplement of 139°?
The supplement of 139° is 41°, because 139° + 41° = 180°. A 139° angle has no complement, because it is already larger than 90°.
How many radians is 139 degrees?
139° = 139π/180 radians ≈ 2.426 rad. To convert degrees to radians, multiply by π/180: 139 × π/180 = 139π/180.
How do I measure a 139° angle on my screen?
Open the online protractor with 139° preset, or type 139 into its "Type an angle" box. You can then drag the arms onto your own lines to compare.
