Advanced Geometry

Measuring Reflex Angles (180° to 360°)

Step-by-step instructions for measuring reflex angles between 180 and 360 degrees using 360-degree protractor mode.

Target Angle
240°
Angle Type
Reflex Angle (240°)
Complementary
N/A
Supplementary
N/A

How to Measure This Angle on an Image or Photo

A reflex angle is an angle greater than 180° but less than 360°. Standard 180° semicircular protractors cannot measure reflex angles directly without subtracting from 360°. Enable 360° Mode on our online protractor to measure reflex angles directly.

Visual Diagram: 240° Angle Illustration
240°

Step-by-Step Measurement Procedure

  1. Upload your image: Drag and drop a photo or blueprint onto the Online Protractor canvas.
  2. Position Point B (Vertex): Drag the central vertex dot directly onto the corner or angle origin.
  3. Align Ray A (Baseline): Drag the left handle so ray A aligns perfectly with your reference line.
  4. Adjust Ray C (Angle Ray): Drag the right handle until ray C lies exactly along the sloped edge.
  5. Read Angle Output: The tool displays degrees, radians, complementary, and supplementary angles in real time.

Measure Your Angle Now

Upload any photo or image to measure angles with sub-degree accuracy in your browser.

Open Online Protractor Tool