Whether an angle is obtuse or not depends on its size and shape. An angle is composed of two rays, lines that have only one endpoint and travel infinitely in a single direction, with the same endpoints. The distance between these two rays, or legs, is measured in degrees. The angle's shape and size are interrelated --- angles with larger measurements have rays that open wider, and those with smaller measurements are narrower. An obtuse angle has a larger measurement that falls within a specified range of degrees. Identifying an obtuse angle can help you in recognizing and solving different types of triangles and other geometric shapes.
Instructions
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1
Place the protractor's center point, where the lines for 0 degrees and 90 degrees intersect, onto the vertex of the angle, lining up the 0-degree line with a leg of the angle.
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2
Record the number of degrees that the other leg intersects along the protractor's top. Record the number from the ascending degrees if the angle opens to the right or the descending degrees if the angle opens to the left.
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3
Check if the measurement is larger than 90 degrees and less than 180 degrees. If the degree measurement falls into this range, the angle is obtuse.