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Transcript
```Using the ClassPad’s Geometry within eActivity
This activity gives step by step instructions on how to explore the
relationship of the angle formed by a tangent to a circle with a chord and
the arc angle of the chord.
Goal – to have students understand the relationship between the angles
formed by a tangent to a circle with a chord and the arc angle of the chord.
Students will discover the missing word in the statement:
The angle formed by a tangent and a chord is equal to ________ the
measure of the intercepted arc.
To begin, select
eActivity.
window is cluttered,
select File then New.
Select OK!
In the steps that follow, we will:
• Draw a circle
• Draw a tangent to the circle
• Draw a chord
• Measure angles
• Create an animation
Casio Education Technology M.R.D. Center
Portland, Oregon
1
1st
We need to insert a
Geometry strip into our
eActivity window.
•
Open the Insert
•
Select Geometry
2nd
Draw a circle
•
Select
(circle icon)
•
Tap the Geometry
window twice
•
Or, you can tap once,
release, then drag
First tap a
center point.
Second
tap…
3rd
Draw a tangent to the
circle:
•
(tangent to
Select
curve icon)
•
Tap a point on the
circles circumference
Casio Education Technology M.R.D. Center
Portland, Oregon
2
4th
Draw a chord:
•
(line
Select
segment icon)
•
Tap the tangent point
(pt C) to start the
Tap here to
chord
start segment.
•
Tap another point on
the circle to end the
chord
Tap here to
end segment.
5th
Draw two radii to form
•
Tap the tangent point
and then the circles
center
•
Tap the other end of
the chord and then
the circles center
6th
Measuring angles:
•
Tap (to advance the
toolbar)
•
Select the chord and
tangent line by tapping
on them
•
Select the wrong thing?
Just tap in an empty
space to deselect
everything and try
again!
Tap here…
Casio Education Technology M.R.D. Center
Portland, Oregon
3
7th
Working with the angle measure in eActivity:
• Tap in the measurement box to select the angle measure
•
Tap and hold the selected number, then drag it to the eActivity window
•
When you see the cursor blinking in eActivity, drop the number
•
Input a division symbol following the number (tap the
hard key)
Drag right to this spot.
When you see the cursor
8th
Now we need to measure the arc angle:
• Select the arc angle and drag its measure to the eActivity window
•
Drag its measure to the eActivity window
•
Change to the math input mode (tap
•
Press EXE or tap
and select
)
to display your answer as a decimal
Nice number?
Maybe…
Casio Education Technology M.R.D. Center
Portland, Oregon
4
9th
Is there a pattern?:
• Select point D and drag it to another location on the circle
•
Measure the tangent/chord angle and then the arc angle
•
Press EXE or tap
to display your answer as a decimal
10th
Fill in the blank:
The angle formed by a tangent and a chord is equal to ________ the
measure of the intercepted arc.
Fun Bonus…
Animate point D around the circle and view many angle measures in a table.
• Select your circle and
point D
• Select Edit, Animation
and then Add Animation
Casio Education Technology M.R.D. Center
Portland, Oregon
• Select Edit, Animation and
then Go (once)
5
• Advance the toolbar
(tap ). You can also
tap
to resize.
• Select the tangent
chord angle and
then tap
.
• Select the arc angle
and then tap
. Nice
relationship!
Optional…
Can you find a relationship between the angle formed by two intersecting
secants and the arc lengths they intersect? I guess this should be another
activity, but here is a start…
Casio Education Technology M.R.D. Center
Portland, Oregon
6
```
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