> For the complete documentation index, see [llms.txt](https://docs.imerit.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.imerit.net/labeling/labeling-editor-interface/medical-labeling-editor/cobb-angle.md).
# Cobb Angle
The Cobb Angle tool measures the angle between two lines on a medical image, for example along the endplates of two vertebrae. It accounts for the scan's real-world proportions, including views with non-square pixels.
## Creating a Cobb Angle
In the project's label set, create a class with **Cobb Angle** as its tool. This tool is available for medical 3D projects.
In the medical labeling editor, select the class from the **Tools** section on the left. On an axial, coronal, or sagittal slice:
1. Click twice to draw the first line.
2. Click twice to draw the second line.
After the fourth click, Ango Hub displays dashed perpendiculars from the middle of each line, an arc, and the angle in degrees. If the perpendiculars meet outside the image, or the lines are parallel, short dashed perpendiculars and the angle label appear between the lines instead.
A Cobb Angle measurement on a coronal slice.
While drawing, right-click to remove the last point. Changing tools or scrolling to another slice cancels an unfinished drawing.
Parallel lines measure 0°. The angle can exceed 90°, and drawing a line from its other end does not change the measurement.
## Editing a Cobb Angle
Select the object, then drag any of its four points to adjust it. Drag a line to move that line's two points together. The other line stays in place, and the measurement updates while you drag.
## Viewing and Navigating
A Cobb angle appears only in the view and slice where you drew it. Click its row in the **Objects** panel, or hold **Ctrl** and hover over the row, to jump to its slice.
{% hint style="info" %}
Cobb angles cannot be drawn or displayed on oblique views. When you rotate the crosshair with [Reformat](/labeling/labeling-editor-interface/medical-labeling-editor.md#reformat), the two resliced views hide Cobb angles. The view where you rotated the crosshair continues to support them.
{% endhint %}
## Saving, Exporting, and Importing
Save or submit the task to keep the measurement. Exported annotations include the four points, the angle, the perpendicular intersection, and real-world coordinates. Parallel lines have no perpendicular intersection. Coordinates are rounded to three decimal places and angles to two decimal places.
You can import exported Cobb angles into another task. The **Import Labels** screen provides a sample JSON format for Cobb Angle classes.
---
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