In geometry, an angle is the figure formed by two rays sharing a common
endpoint, called the vertex of the angle. The magnitude of the angle is
the "amount of rotation" that separates the two rays, and can be
measured by considering the length of circular arc swept out when one
ray is rotated about the vertex to coincide with the other.(source:
WIKIPEDIA). In this article we see the types of angles in geometry.
There are nine types of angles in geometry.
Types of geometric angles with diagrams
Types:
Acute angle:
An angle whose measure is smaller than 90 degrees, then the angle is acute angle. The following is an acute angle.
Right angle:
An angle whose measure is exactly 90 degrees, then the angle is right angle. The following is a right angle.
Obtuse angle:
An angle whose measure is above 90 degree and also less than 180 degree. Thus, it is between 90 degrees and 180 degrees, and then the angle is obtuse angle. The following is an obtuse angle.
Straight angle:
An angle whose measure is 180 degrees. Thus, a straight angle looks like a straight line. The following is a straight angle.
Reflex angle:
An angle whose measure is above 180 degrees but less than 360 degrees, then the angle is reflex angle. The following is a reflex angle.
Adjacent angles:
Angle with a common vertex and one common side. <1 adjacent="" and="" angles.="" are="" nbsp="" p="">
Complementary angles:
Two angles whose measures add to 90 degrees. Angle 1 and angle 2 are complementary angles, as together they form a right angle.
Note that angle 1 and angle 2 do not have to be adjacent to be complementary as long as they add up to 90 degrees.
Supplementary angles:
Two angles whose measures add to 180 degrees. The following are supplementary angles.
Angles that have a common vertex and whose sides are formed by the same lines. The following (angle 1 and angle 2) are vertical angles.
When two parallel lines are crossed by another line is called Transversal, 8 angles are formed. Take a look at the following figure.
Angles 3,4,5,8 are interior angles
Angles 1,2,6,7 are exterior angles
Alternate interior angles:
In transversal pairs of opposite sides are interior angles.
Such as, angle 3 and angle 5 are alternate interior angles. Angle 4 and angle 8 are also alternate interior angles.
Alternate exterior angles:
In transversal pairs of opposite sides are exterior angles.
Angle 2 and angle 7 are alternate exterior angles.
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Corresponding angles:
Pairs of angles that are in similar positions.
Angle 3 and angle 2 are corresponding angles.
Angle 5 and angle 7 are corresponding angles
Practice for geometry angles:
1) Angle 180° is -------- a) Straight angle b) right angle Answer: Straight angle
2) Angle less than 90° is ------------ a) obtuse angle b) acute angle Answer: Acute angle
Types of geometric angles with diagrams
Types:
Acute angle:
An angle whose measure is smaller than 90 degrees, then the angle is acute angle. The following is an acute angle.
Right angle:
An angle whose measure is exactly 90 degrees, then the angle is right angle. The following is a right angle.
Obtuse angle:
An angle whose measure is above 90 degree and also less than 180 degree. Thus, it is between 90 degrees and 180 degrees, and then the angle is obtuse angle. The following is an obtuse angle.
Straight angle:
An angle whose measure is 180 degrees. Thus, a straight angle looks like a straight line. The following is a straight angle.
Reflex angle:
An angle whose measure is above 180 degrees but less than 360 degrees, then the angle is reflex angle. The following is a reflex angle.
Adjacent angles:
Angle with a common vertex and one common side. <1 adjacent="" and="" angles.="" are="" nbsp="" p="">
Complementary angles:
Two angles whose measures add to 90 degrees. Angle 1 and angle 2 are complementary angles, as together they form a right angle.
Note that angle 1 and angle 2 do not have to be adjacent to be complementary as long as they add up to 90 degrees.
Supplementary angles:
Two angles whose measures add to 180 degrees. The following are supplementary angles.
Types of geometric angles with examples:
Vertical angles:Angles that have a common vertex and whose sides are formed by the same lines. The following (angle 1 and angle 2) are vertical angles.
When two parallel lines are crossed by another line is called Transversal, 8 angles are formed. Take a look at the following figure.
Angles 3,4,5,8 are interior angles
Angles 1,2,6,7 are exterior angles
Alternate interior angles:
In transversal pairs of opposite sides are interior angles.
Such as, angle 3 and angle 5 are alternate interior angles. Angle 4 and angle 8 are also alternate interior angles.
Alternate exterior angles:
In transversal pairs of opposite sides are exterior angles.
Angle 2 and angle 7 are alternate exterior angles.
I am planning to write more post on Sine Cosine Identities, samacheer kalvi books online. Keep checking my blog.
Corresponding angles:
Pairs of angles that are in similar positions.
Angle 3 and angle 2 are corresponding angles.
Angle 5 and angle 7 are corresponding angles
Practice for geometry angles:
1) Angle 180° is -------- a) Straight angle b) right angle Answer: Straight angle
2) Angle less than 90° is ------------ a) obtuse angle b) acute angle Answer: Acute angle
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