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02ps-15 Height Of The Duomo Solution

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    To solve this problem, the first thing I did was say, okay, well,
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    it looks like this is directly in the middle of this building--this spire.
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    I can draw some imaginary line, making this distance 25 m.
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    Now, you could have used trigonometry to solve this question.
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    But there was a trick.
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    You could have solved it in a slightly easier way by using similar triangles.
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    To use the similar triangle method,
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    we notice that this triangle in purple is similar to this triangle in green.
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    Now, what are the dimensions of this green triangle?
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    Well, at 60 m along the base from here, and 15 meters here--
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    simply because this height is 60,
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    and we subtract the 45. What about the purple triangle?
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    Well, the base is 180 m--60 + 35 + 60 plus this 25.
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    The height is unknown.
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    This is what we're solving for. I'm going to erase our man to give ourselves some room.
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    We can set up a ratio.
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    The ratio of this side to that side must be the same as x to 180.
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    We multiply both sides by 180 to solve for x.
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    When we do out the arithmetic, we find x = 45 m,
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    but we also have to add in the original 45 m to get the full height of the Duomo.
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    The answer is that the height of the Duomo is 90 m. Very good work.
Title:
02ps-15 Height Of The Duomo Solution
Video Language:
English
Team:
Udacity
Project:
PH100 - Intro to Physics
Duration:
01:11
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