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Measuring Segments
- Ruler postulate: The points on any line can be paired with real numbers so that, given any two points P and Q on the line, P corresponds to zero, and Q corresponds to a positive number
- If Q is between P and R, then QP + PR = QR
- If PQ + QR = PR, then Q is between P and R
- Pythagorean Theorem: In a right triangle, the sum of the squares of the measures of the legs equals the square of the measure of the hypotenuse
- The distance d between any two points with coordinates (x1, y1) and (x2, y2) is given by the formula

Measuring Segments
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
- Intro
- Segments
- Ruler Postulate
- Segment Addition Postulate
- Segment Addition Postulate
- Pythagorean Theorem
- Pythagorean Theorem, cont.
- Distance Formula
- Extra Example 1: Find Each Measure
- Extra Example 2: Find the Missing Measure
- Extra Example 3: Find the Distance Between the Two Points
- Extra Example 4: Pythagorean Theorem































0 answers
Post by Suneet Dash on May 31, 2011
i must say, great video
0 answers
Post by Ahmed Shiran on June 4, 2011
Great work by Mary...
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Post by Pangayar Selvi Shanmugasundaram on August 9, 2011
realy iam telling, its wonderful vedio...
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Post by Giri Iyer on November 10, 2011
Very well done and explained.. I am teaching my son geometry and these lessons are so clear conceptually that even I can recall these concepts now :)
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Post by Joseph Reich on June 20, 2012
For the question: "Write a mathematical sentence given segments ED and EF." E does not have to be in the middle:
in the case:
E-------D------F
the mathematical sentence would be EF - ED = DF
In the case:
E----F-------------D
the mathematical sentence would be ED - EF = DF
Also, in the question, ED and EF should have a bar over them because you are talking about segments and not measures
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Post by Catherine Henderson on July 31, 2012
Wow,
That was great!
1 answer
Sat Mar 2, 2013 1:53 AM
Post by chun yung on November 27, 2012
I have a question on the distance formula, why do they have to make it (x2-x1)+(y2-y1) if u put (x1-x2)+(y1-y2)u could get the same answer.
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Post by Mohammed Abdullah on December 13, 2012
In the video it shows d=square root x1-x2)squared+(x1+x2) squared, in the quick notes they subtract the square roots.
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Post by Edward Hook on February 18 at 03:04:55 PM
Everybody loves your teaching style Mary and I have to say that I do too!
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Post by Kenneth Montfort on February 18 at 04:11:41 PM
Just a quick heads up, your distance formula in your quick notes is incorrect and you might want to include the correlation between the PyT formula and the distance formula, so that it is clear why you are supposed to add the two components instead of the subtraction that you highlight. It super confused at me at first until I looked it up.
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Post by bo young lee on February 19 at 08:00:51 PM
at the educator.com where can i find more about the
pythagorean theorem???