Definition of obtuse angle
Obtuse angle (du? njia？ O) refers to the angle between two straight lines, two line segments or two rays, which is greater than 90 degrees (π/2 radians) but less than 180 degrees (π radians). In other words, an obtuse angle is an angle greater than a right angle (90 degrees) but less than a right angle (180 degrees).
The obtuse angle has the following characteristics:
The degree of 1 obtuse angle is greater than 90 degrees, so its angle range is between (90 degrees, 180 degrees).
2. The complementary angle of an obtuse angle is an acute angle, that is, the sum of the degrees of the two angles is equal to 180 degrees.
3. The complementary angle of obtuse angle is acute angle, that is, the degrees of two angles add up to 90 degrees.
4. The obtuse angle can't form the inner angle of the triangle, because the sum of the inner angles of the triangle must be less than 180 degrees.
Application of obtuse angle:
In geometry and physics, obtuse angles are often used to describe irregular shapes or certain specific situations in mechanical systems. In architectural design, the understanding of obtuse angle is very important for determining the layout and spatial planning of the interior corner of the house. In the field of mechanical engineering, obtuse angles may also appear in the design and assembly of mechanical parts.
The special feature of obtuse angle is that its two sides extend in opposite directions, so we can easily distinguish it from acute angle (less than 90 degrees) and right angle (equal to 90 degrees) intuitively.
Generally speaking, obtuse angle is a basic concept in geometry, and its characteristics and applications widely exist in daily life and various disciplines. For students, understanding the nature and characteristics of obtuse angle is helpful to improve the understanding ability of geometry and to better apply mathematical knowledge to solve practical problems.