The Geometer’s Sketchpad
®
for TI-89, TI-92 Plus, and
© 2000-2002 KCP Technologies, Inc.
69
Voyage™ 200 PLT User Guide and Reference Manual
Sketchpad measures geometric properties of objects (such as the measure
of a segment’s slope) or of groups of objects (such as the distance between
two points). These measurements change dynamically as you drag and
resize objects. To make a measurement, select the object or objects you
wish to measure and choose the appropriate measurement command from
the
‡
Measure menu.
Sketchpad supports the following measurements:
Command
Required Selection
Result
¨
Length
One or more segments
Length of segment(s)
©
Distance
(between points)
Two points
Distance between points
©
Distance
(point to line)
One point and one
straight object
Shortest (perpendicular)
distance from the point to
the line extending through
the straight object
ª
Perimeter
One or more polygon
interiors
Perimeter of polygon(s)
y
Circumference
One or more circles or
circle interiors
Circumference of circle(s)
z
Angle
Three points, selected
in order A, B, C
Measure of angle ABC
(vertex is second selected
point)
{
Area
One or more circles,
circle interiors, or
polygon interiors
Area of circle(s) or
polygon interior(s)
m
Arc Angle
One circle and two or
three points on that
circle
Measure of arc angle
between the two points
(minor arc, less than
180°); or arc angle
between the first and third
points including the
second (minor or major
arc, less than 360°)
‡
Measure Menu
Measurements reveal relationships in figures crucial for
conjecturing. Using commands in the
‡
Measure menu, you
can measure and calculate any property you like, then watch
measurements and calculations change (or not) as you
change your figure. As usual, to create measurements you
must first identify, through selection, which object(s) you want
to measure. This section explains how to make measurements
and use Sketchpad’s calculator.
About
Measurements
