Math

I'm doing Similarities in class and have no idea how this question works. Any explanations as to how to do this question would be great. Here it is:

Here is a way to find (roughly) the width of a river without crossing it.
Place a stake B on one bank opposite a landmark A on the other bank. Walk a distance of 5m along the bank at right abgles to AB and place another stake C. Walk another 1m in the same direction and place another stake D. Now walk at right angles to BD until A and C are in line, then place a stake E. The width of the river is five times the distance between D and E. Draw a diagram showing this and explain why it works.

  1. 👍 0
  2. 👎 0
  3. 👁 38
  1. I assume you drew it.
    Now angle ABC = angle EDC (both right angles)
    and Angle ACB = angle ECD (opposite angles)
    By the way that means angle BAC=angleDEC because they are complementary to equal angles
    Therefore I claim the triangle CDE is similar to triangle CBA
    Therefore AB/BC=DE/DC because they are corresponding parts of similar shapes
    so
    AB/5 = DE/1
    or
    AB = 5 DE
    So if I measure DE I know AB without swimming

    1. 👍 0
    2. 👎 0
    posted by Damon
  2. Here is a way to find (roughly) the width of a river without crossing it.
    Place a stake B on one bank opposite a landmark A on the other bank. Walk a distance of 5m along the bank at right abgles to AB and place another stake C. Walk another 1m in the same direction and place another stake D. Now walk at right angles to BD until A and C are in line, then place a stake E. The width of the river is five times the distance between D and E. Draw a diagram showing this and explain why it works.

    ..............A
    --------------*-------------------------
    ..............l.*
    ..............l...*
    ..............l.....*....C
    ..............l.......*../
    --------------*---------*.*D
    ..............B...........*E

    BC = 5, CD = 1

    Triangles ABC and EDC are similar.

    Therefore, AB/DE = BC/CD
    Since, BC = 5 and CD = 1, AB = 5DE.

    1. 👍 0
    2. 👎 0
    posted by tchrwill

Respond to this Question

First Name

Your Response

Similar Questions

  1. ENGLISH

    Prewriting: Choosing Your Topic Use the chart below to take notes on two literary works that you have found while browsing. These two works should have enough similarities to make connections between them and to draw comparisons.

    asked by I NEED HELP FAST PLEASE!!!!! on June 4, 2016
  2. math plz help!!!!!!

    What do angles, acute angles, and complementary angles have in common??? they are all angles duh! my teacher said that that's too obvious Please check your book for the similarities. This site also has several explanations about

    asked by frank on January 18, 2007
  3. Art

    Think about how different class systems of people are represented during Art of Europe and America (1700 - 1900). Looking at the values and representation of values or ideas, please compare and contrast the visual subject, form,

    asked by Amy on July 2, 2015
  4. English

    Hi, I am reading a story called, "I'm Black, You're White, Who's Innocent" I just have a question on what "account" means in this question? I looked up the definition but came up with many. Could someone explain to me this

    asked by Kuromi on October 15, 2009
  5. Biology helppppppp

    1. Why was communication through books, letters, and lectures such an important factor in the development of the cell theory? What do you think would happen if scientists today were unable to communicate with each other? In

    asked by Maya on October 16, 2006
  6. Art

    Writeacher, could you please check these questions? Thank you. I need to express question number 3 in a different way. 1)Briefly analyze the works of at least two authors (also: of those authors?) (we dealt with in class) who

    asked by Mike on June 18, 2012
  7. English

    Hi for my english class, we have to make an invention using cheap material that is useful, original, and provides a solution to a problem. We actually have to show the class like a prototype of it and I have no idea what to do!

    asked by John on December 5, 2010
  8. psychology

    I would like the entire class to identify the major similarities and differences that exists between the American and European traditions of psychology. Please post a response to this message that includes at least two

    asked by tom on August 6, 2008
  9. sci 207

    The idea of tectonic plates shifting across the earth’s surface is central to explanations of geologic processes. Why is this idea still called the “theory” of plate tectonic movement

    asked by tamika on July 6, 2011
  10. Photojournalism

    What exactly is Photojournalism? Of course I have googled it but I don't exactly have a good idea of how it would be like as a high school class? Does anyone have an idea on what we would be doing in that class?

    asked by Anonymous on May 24, 2017

More Similar Questions