At 121°, this is an obtuse angle, opened up past a square corner but not yet flat. Its supplement is 59°, so a 121° angle and a 59° angle side by side make a straight line.
121° is 121/360 of a full circle, or 121π/180 radians. If you face north and turn 121° clockwise, you end up facing between ESE and SE (closest to east-southeast (ESE)).
121° angle facts
| Angle type | Obtuse angle (between 90° and 180°) |
|---|---|
| Supplement (adds to 180°) | 59° |
| Explement (adds to 360°) | 239° |
| Radians | 121π/180 ≈ 2.111848 |
| Gradians | 134.4444 grad |
| Fraction of a turn | 121/360 (33.61%) |
| Degrees, minutes, seconds | 121° 0′ 0″ |
| Compass bearing | between ESE and SE (closest to east-southeast (ESE)) |
Trigonometric values of 121°
| Function | Value |
|---|---|
| sin 121° | 0.857167 |
| cos 121° | −0.515038 |
| tan 121° | −1.664279 |
121° on a protractor
How to draw a 121° 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 121° 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 121°.
Drawing it a 121° angle without a protractor (rise and run method)
- 121° = 180° − 59°. Draw a straight line, pick a vertex on it, and build a 59° angle on one side as follows; the angle on the other side of the new line is 121°.
- Draw a straight baseline and measure 6.01 inches (about 6″) 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 59°, because tan 59° ≈ 1.6643.
Where you see 121° angles
- The Earth turns 121° on its axis in about 8 h 4 min.
- Obtuse angles like 121° appear in reclining chair backs, open laptop screens, fan blades, and the corners of many-sided polygons.
Related angles
121° angle FAQ
What type of angle is 121°?
A 121° angle is an obtuse angle, because it is between 90° and 180°.
What is the supplement of 121°?
The supplement of 121° is 59°, because 121° + 59° = 180°. A 121° angle has no complement, because it is already larger than 90°.
How many radians is 121 degrees?
121° = 121π/180 radians ≈ 2.1118 rad. To convert degrees to radians, multiply by π/180: 121 × π/180 = 121π/180.
How do I measure a 121° angle on my screen?
Open the online protractor with 121° preset, or type 121 into its "Type an angle" box. You can then drag the arms onto your own lines to compare.
