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3. Length of a Line Segment Learning Goals: To recall Pythagoras’ Theorem To use the theorem to calculate the length of a line To develop a formula for calculating length. Length of A Line Segment.
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3 Length of a Line Segment Learning Goals: To recall Pythagoras’ Theorem To use the theorem to calculate the length of a line To develop a formula for calculating length
Length of A Line Segment • What could I use to measure the length of the line AB? Draw a triangle and use Pythagorean Theorem y (6, 3) B c2 = a2 + b2 c2 = 42 + 22 c2 = 16 + 4 c2 = 20 c = Exact Answer c = 4.47 Approx. Answer 3 2 2 A 1 4 (2, 1) 0 6 7 -7 -5 -6 -4 -3 -2 -1 1 2 3 4 5 -1 -2 -3
Length of A Line Segment • What is the length of the line CD? c2 = a2 + b2 c2 = 42 + 52 c2 = 16 + 25 c2 = 41 c = (Exact) c = 6.40 (Approximate) y 3 2 C (-4, 1) 1 0 6 7 -7 -5 -6 -4 -3 -2 -1 1 2 3 4 5 -1 4 -2 (1, -3) -3 D 5
Length of A Line Segment • We don’t want to have to draw in a triangle each time we need to calculate the length of a line segment. • Let’s develop a formula (using the Pythagorean Theorem) to calculate the length of a line segment.
Length of A Line Segment • What is the length of the line between the points (1, 6) and (5, 9)? c2 = a2 + b2 c2 = c = (5, 9) a (9-6=3) (1, 6) b (5-1=4)
Length of A Line Segment • What is the length of the line between the points (1, 6) and (5, 9)? = = 5 (5, 9) (1, 6)
Length of A Line Segment • What is the length of the line between the points (-2, 1) and (4, 10)? = (4, 10) (-2, 1)
. Classify the triangle by side length. Recall: Equilateral – 3 equal sides Isosceles – 2 equal sides Scalene – No equal sides Find the exact length of each side of ABC
. Classify the triangle by side length. Find the exact length of each side of ABC There are no equal sides ABC is scalene.
Homework – Length of a Line Segment • Page 71 # 1a-f, 5ab, 8, 9, 11, 18ac