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The Midsegment Theorem. Goal 1 Using Midsegments of Triangles. Goal 2 Using Properties of Midsegments. Triangle Midsegment Theorem. If a segment joins the midpoints of two sides of a triangle, then the segment is parallel to the third side and is half as long.
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The Midsegment Theorem Goal 1 Using Midsegments of Triangles. Goal 2 Using Properties of Midsegments.
Triangle Midsegment Theorem • If a segment joins the midpoints of two sides of a triangle, then the segment is parallel to the third side and is half as long.
Using Midsegments of a Triangle a) In XYZ, which segment is parallel to b) Find YZ and XY
Quick Check: Find the m<VUZ. X 65O U Z Y V
Example 1 Identifying Parallel Segments • What are the three pairs of parallel segments in triangle DEF? • RS || ____ • ST || ____ • TR || ____
Example 2 In the diagram, ST and TU are midsegments of triangle PQR. Find PR and TU. 5 ft 16 ft TU = ________ PR = ________
Example 3 In the diagram, XZ and ZY are midsegments of triangle LMN. Find MN and ZY. 14 cm 53 cm ZY = ________ MN = ________
Example 4 Finding Lengths • In triangle QRS, • T, U, and B are midpoints. • What are the lengths of TU, UB, and QR?
Example 5 Using Midsegments of a Triangle Find JK and AB 12 5 JK = ________ AB = ________
52 3x- 4 Example 6 In the diagram, ED and DF are midsegments of triangle ABC. Find the value of x and DF. x = ________ 10 DF = ________ 26
Example 7 Given: DE = x + 2; BC = Find the value of x and DE. x + 2
Example 7 are midsegments in XYZ. Find the perimeter of XYZ.
Example 8 Given: X, Y, and Z are the midpoints of AB, BC, and AC respectively. AX = 2; XY = 3; BC = 9 Find the perimeter of ABC. (it’s a decimal)
5-1 Daily Quiz 12/1 In XYZ, M, N and P are the midpoints. The Perimeter of MNP is 64. a) Find NP. b) Find perimeter of XYZ a) NP + MN + MP = 64 (Definition of Perimeter) NP + + = 64 NP + = 64 NP = b) P = XY + YZ + ZX P = ___ + ___ + ____ P = ______ x 24 M P 22 Y Z N