A 125° angle is obtuse because it is greater than 90° and less than 180°. Its supplement is 55°, so a 125° angle and a 55° angle side by side make a straight line.
125° is 25/72 of a full circle, or 25π/36 radians. If you face north and turn 125° clockwise, you end up facing between ESE and SE (closest to southeast (SE)).
125° angle facts
| Angle type | Obtuse angle (between 90° and 180°) |
|---|---|
| Supplement (adds to 180°) | 55° |
| Explement (adds to 360°) | 235° |
| Radians | 25π/36 ≈ 2.181662 |
| Gradians | 138.8889 grad |
| Fraction of a turn | 25/72 (34.72%) |
| Degrees, minutes, seconds | 125° 0′ 0″ |
| Compass bearing | between ESE and SE (closest to southeast (SE)) |
Trigonometric values of 125°
| Function | Value |
|---|---|
| sin 125° | 0.819152 |
| cos 125° | −0.573576 |
| tan 125° | −1.428148 |
125° on a protractor
How to draw a 125° 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 125° 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 125°.
Drawing it a 125° angle without a protractor (rise and run method)
- 125° = 180° − 55°. Draw a straight line, pick a vertex on it, and build a 55° angle on one side as follows; the angle on the other side of the new line is 125°.
- Draw a straight baseline and measure 7 inches (about 7″) 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 55°, because tan 55° ≈ 1.4281.
Where you see 125° angles
- The Earth turns 125° on its axis in about 8 h 20 min.
- Obtuse angles like 125° appear in reclining chair backs, open laptop screens, fan blades, and the corners of many-sided polygons.
Related angles
125° angle FAQ
What type of angle is 125°?
A 125° angle is an obtuse angle, because it is between 90° and 180°.
What is the supplement of 125°?
The supplement of 125° is 55°, because 125° + 55° = 180°. A 125° angle has no complement, because it is already larger than 90°.
How many radians is 125 degrees?
125° = 25π/36 radians ≈ 2.1817 rad. To convert degrees to radians, multiply by π/180: 125 × π/180 = 25π/36.
How do I measure a 125° angle on my screen?
Open the online protractor with 125° preset, or type 125 into its "Type an angle" box. You can then drag the arms onto your own lines to compare.
