Sharp EL9900 manual Parallel and Perpendicular Lines

EL-9900 Graphing Calculator

Parallel and Perpendicular Lines

Parallel and perpendicular lines can be drawn by changing the slope of the linear equation and the y intercept. A linear equation of y in terms of x can be expressed by the slope- intercept form y = mx + b, where m is the slope and b is the y-intercept.

Parallel lines have an equal slope with different y-intercepts. Perpendicular lines have slopes that are negative reciprocals of each other (m = - m1 ). These characteristics can be verified by graphing these lines.

Example

Graph parallel lines and perpendicular lines.

1. Graph the equations y = 3x + 1 and y = 3x + 2.

2. Graph the equations y = 3x - 1 and y = - 31 x + 1.

Before	There may be differences in the results of calculations and graph plotting depending on the setting.
Starting	Return all settings to the default value and delete all data.

Set the zoom to the decimal window:

ZOOM C

(

ENTER ALPHA

)

7

Step & Key Operation Display Notes

1-1

1-2

2-1

Enter the equations y = 3x + 1 for Y1 and y = 3x + 2 for Y2.

Y=		3	X/ /T/n		+	1	ENTER
3		n	+	2
	X/ /T/

View the graphs.

GRAPH

Enter the equations y = 3x - 1 for Y1 and y = - 31 x + 1 for Y2.

Y= CL 3 X//T/n — 1 ENTER

CL (-) 1 a/b 3 X/ /T/n

+ 1

These lines have an equal slope but different y-intercepts. They are called parallel, and will not intersect.

3-2