A 131° angle is obtuse because it is greater than 90° and less than 180°. Its supplement is 49°, so a 131° angle and a 49° angle side by side make a straight line.
131° is 131/360 of a full circle, or 131π/180 radians. If you face north and turn 131° clockwise, you end up facing between ESE and SE (closest to southeast (SE)).
131° angle facts
| Angle type | Obtuse angle (between 90° and 180°) |
|---|---|
| Supplement (adds to 180°) | 49° |
| Explement (adds to 360°) | 229° |
| Radians | 131π/180 ≈ 2.286381 |
| Gradians | 145.5556 grad |
| Fraction of a turn | 131/360 (36.39%) |
| Degrees, minutes, seconds | 131° 0′ 0″ |
| Compass bearing | between ESE and SE (closest to southeast (SE)) |
Trigonometric values of 131°
| Function | Value |
|---|---|
| sin 131° | 0.75471 |
| cos 131° | −0.656059 |
| tan 131° | −1.150368 |
131° on a protractor
How to draw a 131° 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 131° 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 131°.
Drawing it a 131° angle without a protractor (rise and run method)
- 131° = 180° − 49°. Draw a straight line, pick a vertex on it, and build a 49° angle on one side as follows; the angle on the other side of the new line is 131°.
- Draw a straight baseline and measure 8.69 inches (about 8 11/16″) along it from the vertex.
- At that mark, draw a line straight up at 90° and measure exactly 10 inches up it.
- Join the top mark to the vertex. The angle at the vertex is 49°, because tan 49° ≈ 1.1504.
Where you see 131° angles
- The Earth turns 131° on its axis in about 8 h 44 min.
- Obtuse angles like 131° appear in reclining chair backs, open laptop screens, fan blades, and the corners of many-sided polygons.
Related angles
131° angle FAQ
What type of angle is 131°?
A 131° angle is an obtuse angle, because it is between 90° and 180°.
What is the supplement of 131°?
The supplement of 131° is 49°, because 131° + 49° = 180°. A 131° angle has no complement, because it is already larger than 90°.
How many radians is 131 degrees?
131° = 131π/180 radians ≈ 2.2864 rad. To convert degrees to radians, multiply by π/180: 131 × π/180 = 131π/180.
How do I measure a 131° angle on my screen?
Open the online protractor with 131° preset, or type 131 into its "Type an angle" box. You can then drag the arms onto your own lines to compare.
