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Section 4.7 Medians, Altitudes, and Perpendicular Bisectors. WARM UP. Activity Part 1. Draw a triangle. Label it ∆ BOY. Measure each side of the triangle. Find and mark the MIDPOINT of each side. Activity Part 2. Draw a line connecting Point B to the MIDPOINT on the OPPOSITE SIDE.
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Section 4.7 Medians, Altitudes, and Perpendicular Bisectors WARM UP
Activity Part 1 • Draw a triangle. • Label it ∆BOY. • Measure each side of the triangle. • Find and mark the MIDPOINT of each side.
Activity Part 2 • Draw a line connecting Point B to the MIDPOINT on the OPPOSITE SIDE. • Draw a line connecting Point O to the MIDPOINT on the OPPOSITE SIDE. • Draw a line connecting Point Y to the MIDPOINT on the OPPOSITE SIDE.
What is a Median? • A segment from a vertex to the midpoint of the opposite side. • Always three medians. • See the medians for a given triangle.
What is a Centroid? • Centroid: the point where all three medians meet • The medians of a triangle divide one another into ratios of 2:1. x = 6 x y 3 11 y = 5.5
Activity 2 • Draw a triangle. • Label it ∆ WIG. • Draw a segment from W to the opposite side so that it makes a right angle with that side.
What is an Altitude? • The perpendicular segment from a vertex to the opposite side. • Altitudes can be drawn OUTSIDE of the triangle.
Which line is the median? Which line is the altitude? a b
What are Perpendicular Bisectors? • A line or ray that is perpendicular to the segment at its midpoint. • Does NOT have to start at a VERTEX
Perpendicular Bisectors • What is true of AB and AC?
Circumcenter: point where three perpendicular bisectors meet.
TOGETHER, OPEN YOUR TEXTBOOK • Page 155 - Classroom Exercises • #1-6
Partner Practice • Page 157 # 19 (a, b, and c) • TO BE HANDED IN! Make it neat. • I only need one per group.