Obtuse Angle

Definition

An obtuse angle is an angle that measures more than 90 degrees but less than 180 degrees. It is one of the three main types of angles, the other two being acute angles (less than 90 degrees) and right angles (exactly 90 degrees). Obtuse angles are an important concept in the study of various geometric shapes, including rectangles, triangles, and trapezoids.

5 Must Know Facts For Your Next Test

1. Obtuse angles are commonly found in the study of triangles, where one of the three angles is always an obtuse angle.
2. In a rectangle, the four angles are all right angles, measuring exactly 90 degrees each.
3. Trapezoids can have one pair of opposite angles that are obtuse angles.
4. The sum of the angles in a triangle always equals 180 degrees, so if one angle is obtuse, the other two angles must be acute.
5. Obtuse angles can be used to create unique and interesting geometric designs and patterns.

Review Questions

• How can the presence of an obtuse angle in a triangle be used to determine the properties of the other two angles?
  • If a triangle contains an obtuse angle, the other two angles in the triangle must be acute angles. This is because the sum of the three angles in a triangle always equals 180 degrees. Since an obtuse angle measures more than 90 degrees, the remaining two angles must be less than 90 degrees to ensure the total is 180 degrees.
• Explain how obtuse angles can be used to create unique geometric designs and patterns.
  • Obtuse angles, when combined with other types of angles, can be used to construct a variety of interesting and visually appealing geometric shapes and patterns. By strategically placing obtuse angles within a design, designers can create dynamic, asymmetrical compositions that challenge the traditional symmetry often associated with geometric art. The versatility of obtuse angles allows for the creation of complex, yet visually striking, designs that can be used in a wide range of applications, from architectural elements to textile patterns.
• Analyze the role of obtuse angles in the properties of trapezoids, and how this differs from their role in rectangles and triangles.
  • In a trapezoid, the presence of an obtuse angle is more flexible compared to its role in rectangles and triangles. While rectangles have four right angles and triangles have at most one obtuse angle, trapezoids can have one pair of opposite angles that are obtuse. This unique property of trapezoids allows for a greater variety of shapes and configurations, as the obtuse angles can be strategically placed to create different types of trapezoids, each with their own distinct characteristics and applications. The versatility of obtuse angles in trapezoids is a key factor that distinguishes this geometric shape from others, such as rectangles and triangles, where the role of obtuse angles is more limited or prescribed.

Related terms

Acute Angle:

An angle that measures less than 90 degrees.

Right Angle:

An angle that measures exactly 90 degrees.

Reflex Angle: An angle that measures more than 180 degrees but less than 360 degrees.