all farmul lines and angles
Answers
Here are some basic definitions and properties of lines and angles in geometry. These concepts are tested in many competitive entrance exams like GMAT, GRE, CAT.
Line segment: A line segment has two end points with a definite length.
line segment
Ray: A ray has one end point and infinitely extends in one direction.
ray
Straight line: A straight line has neither starting nor end point and is of infinite length.
line segment
Acute angle: The angle that is between 0° and 90° is an acute angle, ∠A in the figure below.
acute angle
Obtuse angle: The angle that is between 90° and 180° is an obtuse angle, ∠B as shown below.
obtuse angle
Right angle: The angle that is 90° is a Right angle, ∠C as shown below.
right angle
Straight angle: The angle that is 180° is a straight angle, ∠AOB in the figure below.
Supplementary angles:
supplementary angles
In the figure above, ∠AOC + ∠COB = ∠AOB = 180°
If the sum of two angles is 180° then the angles are called supplementary angles.
Two right angles always supplement each other.
The pair of adjacent angles whose sum is a straight angle is called a linear pair.
Complementary angles:
complementary angles
∠COA + ∠AOB = 90°
If the sum of two angles is 90° then the two angles are called complementary angles.
Adjacent angles:
The angles that have a common arm and a common vertex are called adjacent angles.
In the figure above, ∠BOA and ∠AOC are adjacent angles. Their common arm is OA and common vertex is ‘O’.