Is This Answer Correct? Multiplying 10x and 12 by Opposite Values

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Homework Help Overview

The discussion revolves around a problem involving rates of change in a geometric context, specifically related to an isosceles triangle. The original poster questions the correctness of a solution involving the multiplication of certain values, referencing a base measurement and its rate of change.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to verify the correctness of a solution by questioning the multiplication of specific values related to the base and its rate of change. Some participants inquire about the rationale behind multiplying the base by the rate of change, while another participant raises a separate but related question about a different homework problem involving the rate of change of a vertex angle.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and questioning the assumptions made in the original solution. Some guidance has been offered regarding the rates of change involved, but no consensus has been reached on the correctness of the original answer.

Contextual Notes

There are indications of confusion regarding the application of rates of change in the context of the problems presented. Additionally, one participant is advised to start a new thread for their question, suggesting that the original thread may not be the appropriate place for their inquiry.

indigo1
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my question is... is this answer correct? for the last step. WOULDNT you multiply 10x by .5 and 12 by .2? the opposite of what this answer is? Itsays BASE is 10 in and BASE chagnges at .5 in per second
problem:
i45.tinypic.com/xknbci.png
answer:
i50.tinypic.com/2qcnsyv.jpg

this is what i get...

i50.tinypic.com/124cxgy.jpg
 
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indigo1 said:
my question is... is this answer correct? for the last step. WOULDN'T you multiply 10[STRIKE]x[/STRIKE] by .5 and 12 by .2? the opposite of what this answer is? It says BASE is 10 in and BASE changes at .5 in per second
problem:
i45.tinypic.com/xknbci.png
answer:
i50.tinypic.com/2qcnsyv.jpg

this is what i get...

i50.tinypic.com/124cxgy.jpg
Hello indigo1. Welcome to PF !

Why would you want to multiply the base by the rate of change of the base? Even your working has [itex]\displaystyle b\frac{dh}{dt}[/itex] and [itex]\displaystyle h\frac{db}{dt}\ .[/itex]

dh/dt is -0.2 in/sec and db/dt is 0.5 in/sec !

BTW: Below are your images, displayed so others can see them.

attachment.php?attachmentid=48210&stc=1&d=1339361547.png


attachment.php?attachmentid=48211&stc=1&d=1339361619.jpg


attachment.php?attachmentid=48212&stc=1&d=1339361660.jpg
 

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  • 124cxgy.jpg
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This was really helpful
But i was wondering if this is the same for my HW problem i applied the same A' equation but instead looked for the db/dt and i got -3/2 idk if this is right.
"The base of an isosceles triangle is 6 feet. If the altitude is 4 feet and increasing at the rate of 2 inches per minute, at what rate is the vertex angle changing?"
I will really appreciate for your help.
 
seawolf23, instead of tacking your question onto the end of a question from almost two years ago, please start a new thread. Be sure to use the homework template, and include the problem statement and the work you have done.
 

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