Bài giảng Unit 10: Midpoint of a line segment

Unit 10MIDPOINT OF A LINE SEGMENT1Teacher: DO THI DOAN HIENClass: 6A111/01/2016On the ray Ox, draw two line segments OM and ON so that OM=3cm, ON=6cm. compute the length of MN? Compare OM and MNREVIEW2QUESTIONO٠x٠٠MN3cm6cm On the ray Ox, we have OM MN = 6 – 3 	=> MN = 3(cm)So : MN =3 cm0OM = MNPoint M divides line segment ON into 2 congruent parts. On the ray Ox, draw two line segments OM and ON so that OM=3cm, ON=6cm. Calculate the length of MN? Compare OM and MNMr. M, what’s your name? OM = 3cm MN =3cmsolutionThe point M of line segment AB is the point which is located between A, B and has the equal distance from A, B. A midpoint divides a line segment into two congruent segments.Note: The midpoint of line segment AB is also known as the central point of line segment ABUNIT 10. MIDPOINT OF A LINE SEGMENT1. DEFINITIONAMBPoint M is midpoint of line segment ABREMEMBER5M is midpoint of line segment ABBMA٠٠٠M is between A, BM is equidistant from A, B (MA = MB)6ABMFig. 2ABMFig. 3BMAFig. 1ABMFig. 4M is not between A, BM is between but not equidistant from A, BM is equidistant from but not between A, BM is between and equidistant from A, BM is not midpoint of line segment ABAPPLY: In each case, is m midpoint of line segment Ab or not, and why? M is not midpoint of line segment ABM is not midpoint of line segment ABM is midpoint of line segment AB2. How to draw the midpoint of a line segment?i) Using straight ruler with measurements For example: 7MNKDraw midpoint K of segment MN=5cm2. How to draw the midpoint of a line segment?ii) Folding paper: Make a midpoint on paper sheet, fold it so that 2 sides overlap to define a midpoint8ABABABABABABABABABABABABABABABABABABM27iii) Folding rope: Using a rope to divide a straight wooden stick into two equal parts 2. How to draw the midpoint of a line segment? Using a rope to measure wooden stick, and then fold it so that two end points overlap each other, using folded rope to identify midpoint of wooden stick.28BMAvi) Using compass29Midpoint geometry in real life30Exercise 63 (Work book Page 126): Select correct answers in the following conclusionsABCDIA = IBAI + IB = ABAI + IB = AB and IA = IB3. DO EXERCISESRIGHTRIGHTWRONGWRONG31practical exerciseDetermine the midpoint of your pen or pencil by preparedrope. You only have 30 seconds for this!!!32MN = 40 cmBonus: Let H is midpoint of line segment MN, and MH=20 cm. Calculate the length of line segment MN?20cm?cmHMN33Consolidating Lesson Remind : when point M is called a midpoint of line segment AB?M is midpoint of line segment ABBMA٠٠٠M is between A, BM is equidistant from A, B (MA = MB)Do homework: 64, 65 workbook p. 126Thanks for your atention34