8th Class Mathematics Introduction to Graphs

Introduction to Graphs

• Bar graph: A bar graph is used to show comparison among categories.

• Pie graph: A pie graph is used to compare parts of whole.

• Histogram: Representation that shows data in intervals.

• Line graph: It shows data that changes continuously over periods of time.

• Linear graph: A straight line graph is called a linear graph.

• The Cartesian system:

(i)A plane is divided into 4 quarters (called quadrants) by two perpendicular lines, intersecting at 0 (called origin). The horizontal line is called the X-axis and the vertical line is called the Y-axis.

(ii) A point is represented by the horizontal distance from the origin called the x-coordinate and by the vertical distance from the origin called the y-coordinate.

(ii) A point is represented by an ordered pair (x, y) where x is the x-coordinate and y is the y-coordinate.

• A graph shows the relation between two variables, one of which is an independent variable (or control variable) and the other a dependent variable.

• Advantages and disadvantages of various graphs: