Triangle Midsegment Theorem Lesson 55 Saxon Geometry
Warm-up Problems: Puzzle Packet
Puzzle Packet
Essential Questions What is a midsegment of a triangle? Which of the side lengths of a triangle is the midsegment’s length half of? Which of the side lengths of a triangle is the midsegment parallel to? How is a midsegment triangle related to the original triangle?
New Concepts: Lesson 55 A midsegment of a triangle is a segment that joins the midpoints of two sides of the triangle. Every triangle has three midsegments. The midsegment is always half the length of the side that does not have a midsegment endpoint on it.
Triangle Midsegment Theorem
Using the Triangle Midsegment Theorem In the diagram, DE is a midsegment of ABC. Find the values of x and y.
Your Turn: Using Triangle Midsegment Thm In the diagram, PQ is a midsegment of LMN. Find the values of x and y.
Theorem 55-2
In the diagram, what are the values of a and b? Using Theorem 55-2 In the diagram, what are the values of a and b?
Identifying Midpoints of Sides of Triangles Triangle MNP has vertices M(-2, 4), N(6, 2), and P(2, -1). QR is a midsegment of MNP. Find the coordinates of Q and R.
Identifying Midpoints of Sides of Triangles Triangle ABC has vertices A(-2, 1), B(4, 3), and C(2,-2). DE is a midsegment of ABC parallel to AC . Find the coordinates of D and E.
Applying Similarity to Midsegment Problems Triangle STU is the midsegment triangle of PQR. a. Show that STU ∼ PQR. b. Find PQ.
Your Turn! Applying Similarity Triangle NOP is the midsegment triangle of KLM. a. Show that KLM ∼ NOP. b. Find the length of LK.
Video Summarizer
Written Practice L55 Practice p. 364 a, b, c, d Please; work with a partner.
Exit Slip p. 366 #15 & #30 Individual Assessment