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Geometry The Triangle Midsegment Theorem. Warm up. Find each length. 1) NX 2) MR 3) NP. P. 1). S. 3. R. X. 4.5. 5.5. M. Q. N. The Triangle Midsegment Theorem.
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Geometry The Triangle Midsegment Theorem CONFIDENTIAL
Warm up Find each length. 1) NX 2) MR 3) NP P 1) S 3 R X 4.5 5.5 M Q N CONFIDENTIAL
The Triangle Midsegment Theorem A midsegment of a triangle is a segment that joins the midpoints of two sides of the triangle. Every triangle has three midsegment, which form the midsegment triangle. Q Y X P R Z CONFIDENTIAL
Examining Midsegments in the coordinate Plane y H(-5, 6) 6 L 4 J(1, 2) K 2 0 x -2 -2 G(-7, -2) Next Page: CONFIDENTIAL
y H(-5, 6) 6 L 4 J(1, 2) K 2 0 x -2 -2 G(-7, -2) Next Page: CONFIDENTIAL
y H(-5, 6) 6 L 4 J(1, 2) K 2 0 x -2 -2 G(-7, -2) CONFIDENTIAL
Now you try! CONFIDENTIAL
The relationship show in Example 1 is true for the three midsegments of every triangle . CONFIDENTIAL
Triangle Midsegment Theorem Theorem 4.1 A Midsegment of a triangle is parallel to a side of the triangle, and its length is half the length of that side. B D E A C CONFIDENTIAL
Using the triangle Midsegment Theorem Find each measure. S U A) UW 5.2 R 41˚ ∆ Midsegment Thm. Substitute 7.4 for ST. Simplify. V 7.4 W T Next Page: CONFIDENTIAL
S B) m/ SVU U 5.2 R 41˚ V 7.4 ∆ Midsegment Thm. Alt. Int. /s Thm. Substitute 41˚ for m/ VUW. W T CONFIDENTIAL
Now you try! 2) Find each measure. a) JL b) PM c) m/ MLK P K J 36 102˚ M N • 72 • b) 43.5 • c)1020 97 L CONFIDENTIAL
Indirect Measurement Application Anna wants to find the distance across the base of Capulin Volcano, an extinct volcano in New Mexico. She measures a triangle at one side of the volcano as shown in the diagram. What is AE? C ∆ midsegment Thm. Substitute 775 foe BD. Multiply both sides by 2. 920 m 700 m 775 m B D 920 m 700 m E A The distance AE across the base of the volcano is about 1550 meters. CONFIDENTIAL
Now you try! 3) Suppose Anna’s result in Example 3 is correct to check it, she measures a second triangle. How many meters will she measure between H and F? E A 640 m 1005 m H F 3) 640 m 1005 m G CONFIDENTIAL
Now some problems for you to practice ! CONFIDENTIAL
Assessment CONFIDENTIAL
Find each measure. • 2) NM 3) XZ • 4) NZ 5) m/ LMN • 6) m/ YXZ 7) m/ XLM Y 10.2 L 5.6 M 2) 5.1 3) 11.2 4) 5.6 5)290 6)290 7)290 29˚ X Z N CONFIDENTIAL
8) In this A-frame house, the width of the first floor XZ is 30 feet. The second floor CD is slightly above and parallel to the midsegment of ∆XYZ. Is the width of the second floor more or less than 5 yards? Explain. Y C D X Z CONFIDENTIAL
Let’s review The Triangle Midsegment Theorem A midsegment of a triangle is a segment that joins the midpoints of two sides of the triangle. Every triangle has three midsegment, which form the midsegment triangle. Q Y X P R Z CONFIDENTIAL
Examining Midsegments in the coordinate Plane y H(-5, 6) 6 L 4 J(1, 2) K 2 0 x -2 -2 G(-7, -2) Next Page: CONFIDENTIAL
y H(-5, 6) 6 L 4 J(1, 2) K 2 0 x -2 -2 G(-7, -2) Next Page: CONFIDENTIAL
y H(-5, 6) 6 L 4 J(1, 2) K 2 0 x -2 -2 G(-7, -2) CONFIDENTIAL
The relationship show in Example 1 is true for the three midsegments of every triangle . CONFIDENTIAL
Theorem 4.1 Triangle Midsegment Theorem A Midsegment of a triangle is parallel to a side of the triangle, and its length is half the length of that side. B D E A C CONFIDENTIAL
Using the triangle Midsegment Theorem Find each measure. S U A) UW 5.2 R 41˚ ∆ Midsegment Thm. Substitute 7.4 for ST. Simplify. V 7.4 W T Next Page: CONFIDENTIAL
S B) m/ SVU U 5.2 R 41˚ V 7.4 ∆ Midsegment Thm. Alt. Int. /s Thm. Substitute 41˚ for m/ VUW. W T CONFIDENTIAL
Indirect Measurement Application Anna wants to find the distance across the base of Capulin Volcano, an extinct volcano in New Mexico. She measures a triangle at one side of the volcano as shown in the diagram. What is AE? C ∆ midsegment Thm. Substitute 775 foe BD. Multiply both sides by 2. 920 m 700 m 775 m B D 920 m 700 m E The distance AE across the base of the volcano is about 1550 meters. A CONFIDENTIAL
You did a great job today! CONFIDENTIAL