PART 1 of SECANTS
#1 Parallel lines and arcs
In sketchpad, create a circle.
Click on the arrow.
Click on the circle, and construct a point on the circle.
Right click on the point and change the color.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
Click on two of your points. Construct a line ( which is a SECANT). This line will be selected, which
you want.
Click on your third point and Construct a Parallel line. (which makes another SECANT). This line will
be selected, which you want.
Click on the circle.
Construct the Intersections. This will make a new point where the second secant meets the circle.
Click on the white space.
Click two points that are near each other but on different secants.
Click the circle.
Measure the Arc Angle.
Click the white space.
Click the other two points that are near each other but on different secants.
Click the circle.
Measure the Arc Angle.
What do you know about the arc angles created by parallel lines?
PART 2
Click File then New Sketch
In sketchpad, create a circle.
Click on the arrow.
Click on the circle, and construct a point on the circle.
Right click on the point and change the color.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
You now have 4 non-red points on the circle.
Choose two non-adjacent points by clicking. Construct a line (SECANT).
Click on the white space.
Choose the other two non-adjacent points by clicking. Construct a line (SECANT), which is
highlighted..
Your two secants intersect. Click on the first secant too. Both secants should be highlighted.
Construct the Intersection.
Measure the arcs opposite each other. Measure the angle of intersection.
Can you find a relationship between the arc measures and the angle of intersection?
PART 3
Click File then New Sketch
In sketchpad, create a circle.
Click on the arrow.
Click on the circle, and construct a point on the circle.
Right click on the point and change the color.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
Click on the circle, and construct a point on the circle.
Click on the white space.
You now have 4 non-red points on the circle.
Choose two adjacent points by clicking. Construct a line (SECANT).
Click on the white space.
Choose the other two adjacent points by clicking. Construct a line (SECANT), which is highlighted..
Your two secants intersect. Click on the first secant too. Both secants should be highlighted.
Construct the Intersection, which is outside the circle.
Measure the arcs opposite each other, between the secants. Measure the angle of intersection.
Can you find a relationship between the arc measures and the angle of intersection?