LESSON PLAN Kiea Brown Geometry (5.6/5.7)
Objective: SWBAT use and apply inequalities involving angles and sides of triangles. Application of SAS inequality and SSS inequality to form conclusions about two triangles. (day 32-HONORS)
Warm-Up: SOL and review questions/attendance/checkhw
Presentation: “Triangle Inequalities”……….Storytime
Theorem: The segment from a point to a line is the shortest segment. Draw a picture.
Activity: Protractor, Ruler, Notebook paper (Work together in pairs)
1. Draw a scalene triangle on a sheet of paper or on the dry erase board.
Label the triangle as .
2. Each side of the triangle is measure in ______(what units) and each angle in ______(what units).
Now name each side of the triangle: ______, ______, ______
Now name each angle of the triangle: ______, ______, ______
3. Draw a square around the measure of the longest side.
Draw a square around the angle that lies opposite the longest side.
Make a conjecture about the measures of the angles based upon the measure of the opposite sides.
4. Raise your hand when you have finished for your classgrade
Theorem-In a , if two angles are not congruent then larger side is opposite the larger angle.
(The converse is also true)
In a , if two sides are not congruent then the larger angle is opposite the longer side.
(The converse is also true)
Ex: Name in descending order.
1.2.3.
Theorem- in a the lengths of any two sides must be larger than the third side to form a triangle.
Example-Can the be formed?
4. 7, 7 , 95. 6, 4, 26. 11, 5, 87. 4, 10, 6
Between what two values must the third side lie?
8. 8 and 99. 6 and 1510. 12 and 711. 2.3 and 9.2
SAS inequality- if 2 sides of one are to 2 sides of another and the included angles are not the side opposite the largest < will be greatest.
11.12.13.14.
SSS inequality- if 2 sides of one to 2 sides of another, but the third side of one is greater than the 3rd side the angle opposite the larger side is larger.
15. 16.17.
SAS inequalitydraw conclusions about sides SSS inequality draw conclusions about angles
Class Exercises: use power point examples
Homework: worksheet
1-7. Highlight those that form a triangle. If a triangle can be formed, list the angles in descending order. (Diagrams not drawn to scale)
8-16. Highlight those that form a triangle. If a triangle can be formed, list the sides in ascending order. (Diagrams not drawn to scale)
17. List the sides of in descending order, given:
18. Given with Highlight the true statement(s).
19-25. Determine which side measures will form a triangle. Underline those that form a right triangle. Highlight those that form a obtuse triangle. Put a rectangle around those that form an acute triangle.
2, 3and 49, 10 and 2014, 17 and 313, 4 and 515, 17 and 19
(3, 5), (4, 7) and (7, 6)(1, -5), (-3, 0) and (-1, 0)
26-27. For each of the problems below, highlight the possible values for the third side of the triangle(s)..
side lengths 5 and 9:4, 7.8, 10, 12.9 side lengths 7 and 14: 5, 11, 15, 18, 22
28-29. For each of the problems below, highlight the values that will not form triangle(s).
side lengths 1 and 1: 0.5, 1.9, 2, 8side lengths 18 and 22: 2, 4, 17, 25, 39, 40, 45
30. Find the two longest sides of and
31. Find the two shortest sides of and
32-34. Name the shortest length. 35. Using the diagram, which must be true?
36-38. What can be concluded for each of the three pairs?