1. 1 Objectives: 1. Measure segments. 2. Calculate with measures. 1-2 Linear Measure and Precision

2. What is the difference in accuracy and precision? Accuracy – how close a measured value is to the true or actual value. Precision – how close the measured values are to each other. Low accuracy High Precision High Accuracy Low Precision High Accuracy High Precision

3. Tell how accurate and precise each example is. You Try It: 1. A soccer player always hits the left goal post instead of scoring. 2.A bowler aims for and hits the front pin three times in a row. 3.A basketball player has shot 10 half court shots, He did not make any of them. 4. A man is target shooting, he hits the target 5 times but in a different area each time. 1.Low accuracy High precision 2.High accuracy High precision 3.Low accuracy Low precision 4.High accuracy Low precision

4. 4 Construction of Congruent Segment 1.Draw a segment XY. 2.Elsewhere on the paper, draw a line and a point on the line. Label the point P. 3.Place the compass at point X and adjust the compass setting so that the pencil is at point Y. 4.Using that setting, place the compass at point P and draw an arc that intersects the line. Label the point of intersection Q. PQ XY

5. 5 Construction of Congruent Angle. 1.Draw an angle like < P. 2.Use a straightedge to draw a ray and label the endpoint as T. 3.Place the compass at Point P and draw a large arc that intersects both sides of <P. Label the points of intersection as Q and R. P T Q R Continued……

6. 6 Construction of Congruent Angle – continuation 4.Using the same compass setting, put the compass at point T and draw a large arc that starts above the ray and intersects the ray. Label the point of intersection S. 5.Place the compass on R and adjust pencil to Q. 6.With same compass setting, place compass at S and draw an arc to intersect the larger arc from step 4. 7.Use straightedge to draw P Q R T S U

7. 7 Construction of Segment Bisector 1.Draw a segment and name it. 2.Place the compass at point X. Adjust the compass so that its width is greater than ½XY. 3.Draw arcs above and below. 4.Using same compass setting, place the compass at point Y and draw arcs above and below XY so that they intersect the two arcs previously drawn. Label the points of intersection of the arcs as P and Q. 5.Use straightedge to draw. Label the point where it intersects XY as M. XY P Q M M is the midpoint of.

8. 8 Construction of Angle Bisector 1.Draw an angle <A. 2.Place compass at A and draw a large arc that intersects both sides of <A. Label the points of intersection B and C. 3.With the compass at B, draw an arc in the interior of the angle. A B C Continued……

9. 9 A B C 4.Keeping the same compass setting, place the compass at C and draw an arc that intersects the arc drawn in Step 3. Label the point of intersection D. 5.Draw. Construction of Angle Bisector – continuation D

10. Construction of a perpendicular from a point on the line. A BC n 10 Continued…… 1.Draw line n and mark a point C on the line. 2.Place compass at C and draw arcs to the right & left of C, intersecting the line n. Label the pts. of intersection A & B. 3.Place the compass at A with a setting greater than AC, draw an arc above the line n.

11. 11 Construction of a perpendicular from a point on the line - continuation. 4. Using same compass setting as in Step 3, place the compass at pt. B and draw an arc intersecting the previously drawn. Label the pt. of intersection D. 5.Use a straightedge to draw. A BC n D

12. 12 Construction of a perpendicular from a point not on the line. 1.Draw line n and mark a point Z not on the line. 2.Place compass at Z and draw an arc that intersects line n in two different places. Label the pts. of intersection X & Y. 3.Place the compass at X with a setting greater that ½XY, draw an arc below the line n. n Z X Y Continued……

13. 13 Construction of a perpendicular from a point not on the line - continuation. 4.Using same compass setting as in Step 3, place the compass at pt. Y and draw an arc intersecting the previously drawn. Label the pt. of intersection A. 5.Use a straightedge to draw. n Z X Y A

14. Construction a line parallel to a given line through a point A not on the given line. 1. Construct point Z on the given line. 2. Construct Ray ZA 3. Construct 2 circles or arcs with the same radius from Z and A. Construct points B and C on Ray ZA. 4. Construct the Point of intersection of the Circle and the given line. Call it D. 5. Measure with your compass the opening of ARC BD. 14 Continue …. Z A B C D

15. Construction a line parallel to a given line through a point A not on the given line. 15 1. Construct another circle/arc from C now with the same opening. You will find the point of intersection with Circle A. Call it F. 2. Construct Line AF. 3. We basically constructed a congruent angle to angle Z from Vertex A. 4. By having these two angles congruent we can be certain that the two lines are parallel. Z A B C D F Line AF // Line ZD