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The Distance Between Vertices

  • Thread starter LLS
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[SOLVED] The Distance Between Vertices

Homework Statement



A triangle has vertices at points A, B and C, which are located at (1,0), (-3,0), and (0,5) respectively. What is the distance from the midpoint of AB to point C?

Homework Equations




The Attempt at a Solution



I plotted the triangle. Side AC = 5

The midpoint of AB is at (-1,0)

The distance from the midpoint of AB to C = 5. It's the same as AC.

I think that I am missing something.

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
Hootenanny
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Side AC = 5
No it isn't.
The midpoint of AB is at (-1,0)
Correct :approve:
The distance from the midpoint of AB to C = 5
No it isn't.
It's the same as AC.
Correct :approve:
 
  • #3
symbolipoint
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You correctly chose that the midpoint of AB is (-1, 0); but AC is not equal to 5.

Point C is at (0, 5). Use the distance formula to find the length from point C (-1, 0) to the point (0, 5).
 
  • #4
Hootenanny
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Use the distance formula to find the length from point C (-1, 0) to the point (0, 5).
I'm sure symbolipoint means,

Use the distance formula to find the length from the midpoint of AB (-1, 0) to the point C (0, 5).
 
  • #5
LLS
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You correctly chose that the midpoint of AB is (-1, 0); but AC is not equal to 5.

Point C is at (0, 5). Use the distance formula to find the length from point C (-1, 0) to the point (0, 5).
c^2 = (5-0)^2 + (1-0)^2

c^2 = 25 + 1 = 26

c = 5.097

I still get that the distance = 5.

What did I do wrong?
 
  • #6
Hootenanny
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c^2 = (5-0)^2 + (1-0)^2

c^2 = 25 + 1 = 26

c = 5.097

I still get that the distance = 5.

What did I do wrong?
How is [itex]\sqrt{26} = 5.097... =5[/itex] :surprised?

Now you're just making things up.
 
  • #7
LLS
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How is [itex]\sqrt{26} = 5.097... =5[/itex] :surprised?

Now you're just making things up.
It's what the calculator indicated:

5.097019514 to be exact

I'm lost. Did I do the distance formula calc correctly?
 
  • #8
Hootenanny
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It's what the calculator indicated:

5.097019514 to be exact

I'm lost.
All I'm say is that 5.097019514.... is NOT the same as 5! Therefore, you distance from the midpoint of AB to C is NOT 5.
 
  • #9
LLS
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All I'm say is that 5.097019514.... is NOT the same as 5! Therefore, you distance from the midpoint of AB to C is NOT 5.
I rounded it. I didn't round up to 5.1. I rounded down to 5.

Is 5.097019514 the correct answer?

Have I done any other calcs correctly?

Please steer me towards a calc that works. I don't want to give up.
 
  • #10
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its best if you do not plug in numbers in until the very end. for instance leave sqrt(5) as sqrt(5) and do not put it down as 5.097...
 
  • #11
Hootenanny
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I rounded it. I didn't round up to 5.1. I rounded down to 5.

Is 5.097019514 the correct answer?

Have I done any other calcs correctly?

Please steer me towards a calc that works. I don't want to give up.
Your calculation is correct, your final answer is not. If you are rounding then you should explicitly state the degree of accuracy to which you have quoted the answer. However an exact answer is always preferable, you should leave it in surd form unless instructed otherwise.
 
  • #12
LLS
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Your calculation is correct, your final answer is not. If you are rounding then you should explicitly state the degree of accuracy to which you have quoted the answer. However an exact answer is always preferable, you should leave it in surd form unless instructed otherwise.
Was it the correct calculation? I may have a correct calculation but if the formula was wrong or the values the answer is wrong.

I'm really confused as to what the answer is.
 
  • #13
Hootenanny
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Was it the correct calculation? I may have a correct calculation but if the formula was wrong or the values the answer is wrong.

I'm really confused as to what the answer is.
The formula is correct and the answer is [itex]\sqrt{26}[/itex] as you calculated, there is no need to write it in decimal form (unless stated otherwise). An answer in this form is exact, as opposed to an approximated decimal.

However, if you do wish to write it in decimal form, you must state explicitly the degree of accuracy which you are rounding it to. Simply writing AB=5 is incorrect, but writing AB=5 (1sf) is acceptable.
 
  • #14
LLS
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The formula is correct and the answer is [itex]\sqrt{26}[/itex] as you calculated, there is no need to write it in decimal form (unless stated otherwise). An answer in this form is exact, as opposed to an approximated decimal.

However, if you do wish to write it in decimal form, you must state explicitly the degree of accuracy which you are rounding it to. Simply writing AB=5 is incorrect, but writing AB=5 (1sf) is acceptable.
Thank you
 

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