sson 27 on the coordinate plane applying the...

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LESSON 146 Domain 4: Geometry Duplicating any part of this book is prohibited by law. EXAMPLE A Line segment CD is plotted on the coordinate plane What is the length of ___ CD  ? Identify the coordinates of each endpoint Point C is at (4, 3) Point D is at (10, 11) Apply the Pythagorean theorem a 2 1 b 2 5 c 2 6 2 1 8 2 5 c 2 36 1 64 5 c 2 100 5 c 2 10 5 c The length of ___ CD is 10 units 3 1 How can you find the length of the line segment? The line segment is not horizontal or vertical, so finding the length is not as simple as counting units or subtracting coordinates However, line segment CD can become the hypotenuse of a right triangle, with one horizontal leg and one vertical leg, as shown 7 8 6 5 4 3 2 1 0 9 10 11 12 13 y x 1 2 3 4 5 6 7 8 9 10 11 12 13 D 8 6 C Now you can count units or subtract coordinates to find the lengths of the legs The horizontal leg connects (4, 3) to (10, 3), so subtract the x-coordinates Its length is 10 2 4 5 6 units The vertical leg connects (10, 3) to (10, 11), so subtract the y-coordinates Its length is 11 2 3 5 8 units 2 7 8 6 5 4 3 2 1 0 9 10 11 12 13 y x 1 2 3 4 5 6 7 8 9 10 11 12 13 D C Applying the Pythagorean Theorem on the Coordinate Plane 27 Show another way to draw the right triangle for this problem 7 8 6 5 4 3 2 1 0 9 10 11 12 13 y x 1 2 3 4 5 6 7 8 9 10 11 12 13 D C M O D E L

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LESSON

146 Domain 4: Geometry

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EXAMPLE A LinesegmentCDisplottedonthecoordinateplane .Whatisthelengthof

___CD ?

Identifythecoordinatesofeachendpoint .

PointCisat(4,3) .PointDisat(10,11) .

ApplythePythagoreantheorem .

  a21b25c2

621825c2

361645c2

1005c2

105c

▸Thelengthof___

CD is10units .

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1Howcanyoufindthelengthofthelinesegment?

Thelinesegmentisnothorizontalorvertical,sofindingthelengthisnotassimpleascountingunitsorsubtractingcoordinates .However,linesegmentCDcanbecomethehypotenuseofarighttriangle,withonehorizontallegandoneverticalleg,asshown .

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Nowyoucancountunitsorsubtractcoordinatestofindthelengthsofthelegs .

Thehorizontallegconnects(4,3)to(10,3),sosubtractthex-coordinates .

Itslengthis102456units .

Theverticallegconnects(10,3)to(10,11),sosubtractthey-coordinates .

Itslengthis112358units .

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Applying the Pythagorean Theoremon the Coordinate Plane27

Showanotherwaytodrawtherighttriangleforthisproblem .

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Lesson 27: Applying the Pythagorean Theorem on the Coordinate Plane 147

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EXAMPLE B WhatisthedistancebetweenpointsRandS?

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Howcanyoufindthelengthofthelinesegment?

ConnectpointsRandStoformthehypotenuseofarighttriangle .

Thendrawhorizontalandverticallegs,asshown .

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1ApplythePythagoreantheorem .

  a21b25c2

5211225c2

2511445c2

1695c2

135c

▸ThedistancebetweenpointsRandSis13units .

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WhatisthedistancebetweenpointsTandV?Estimateyouranswertothenearesttenth .

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Practice

148 Domain 4: Geometry

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Determine the length of a line segment with the given endpoints. Use Math Tool: Coordinate Plane.

1. (0,7)and(0,1) 2. (4,8)and(6,8)

Be sure to subtract the lesser coordinate from the greater coordinate.

HINT

3. (21,12)and(21,7)

Determine the length of each line segment. Show your work.

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Lesson 27: Applying the Pythagorean Theorem on the Coordinate Plane 149

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On the town map at right, each unit represents 1 kilometer. Use the town map to answer questions 8 and 9.

8. MaksimjogsdirectlyfromCityHalltothepubliclibrary .Howmanykilometersdoeshejog?Showyourwork .

9. Acrowfliesdirectlyfromthecourthousetothemuseum .Whatdistancedoesthecrowfly?Showyourwork .

Plot the points on the coordinate plane. Then calculate the distance between the two points. Round your answer to the nearest tenth. Show your work.

10. pointV(25,2)andpointW(1,22)

Solve.

11. DRAW DrawadiagonalforrectangleABCDandcalculateitslength .Isitpossibletodrawadifferentdiagonalforthisrectanglethathasadifferentlength?Explain .

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B C

A D

12. COMPARE Compare___

PQ to___

PR  .Whichlinesegmentislonger?Howmanyunitslonger?Showyourwork .

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City HallMonument

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CourthousePublic Library

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Town Map

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