7TH MATHEMATICS
SA1 PREPARATION
(LINES AND ANGLES)
After going through this chapter students will be able to learn
TYPE 1 Some Important
definations
1. Point:-A
fine dot made by a sharp pencil having no length ,breadth and height is called
a point.
2. Line segment:-A geometrical figure
obtained by joining two points is called a line segment. It has definite
length.
3. Line:-If we
extend the two end points in either direction endlessly , we get a line. It has
no length.
4. Ray:-A ray
has only one end point.
5. Angle:-Angle
is formed when lines or lines segments meet.
TYPE 2 Different types of
angles.
1. Complementary angles:-Two angles are said
to be complementary if the sum of their measures is 90.
2. Supplementary angles:-Two
angles are said to be Supplementary if the sum of their measures is 180
3.Adjacent angles:-Two
angles are called adjacent angles if i) they have a common vertex
ii)They have a common arm
iii) Their other arms lie on the opposite sides of the common
arm.
4. Linear pair:-
Two adjacent angles are said to form a linear pair if their non common arms are
two opposite rays.
5. Vertically opposite angles:-
Two angles formed by two intersecting lines having no common arm are called
vertically opposite angles.
TYPE 3 Types of lines
1. Intersecting lines:-
Two lines are said to be intersecting if they have a point in common.
2. Transversal lines:-
A line that intersects two or more lines at distinct points is called a
transversal line.
3. Parrallel lines:-
Two lines are said to be parallel if they lie in the same plane, they do not
intersect when produced indefinitely in either direction.
TYPE 4 Angles formed by two
intersecting lines
1.Corresponding angles
2.Alternate interior angles
3.Alternate angles
4.Alternate exterior angles.
Reference :- 1. Above mentioned types are learning material
.Please refer book also (M.E) *Maths
Exemplar
2. www.dbs7maths.blogspot.in
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