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April 1st, 2019, 06:46 PM   #21
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Quote:
Originally Posted by helpmeddddd View Post
I found the midpoints of HS and MH, found their slopes/gradients, then did the equations of the gradients.
Can you clarify this by giving the coordinates you used for H, S and M, your calculated midpoints and slopes, etc? (Your previous posts aren't entirely consistent.)
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April 1st, 2019, 08:41 PM   #22
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The midpoint of HS = (-63.5,25)

The midpoint of MH = (-72.5,29)

Gradient of HS = -1/14

Gradient of MH = -5/2

Equation of HS is y = 1/14x + 831/28

The equation of MH is y = -5/2x - 609/4


making each equation = each other: 1/14x + 831/28 = -5/2x - 609/4 : x = -71

putting x into an equation I get; 1/14×(times)-71 + 831/28 = 25 y = 25


note / is the fraction sign. Not division sorry about that.


coordinates I used: M (-80,26) H(-65,32) S(-66,18)

When I draw a graph of these midpoints, these intersect at (-71,25).

Last edited by skipjack; April 1st, 2019 at 11:00 PM.
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April 1st, 2019, 08:50 PM   #23
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Quote:
Originally Posted by skipjack View Post
More accurately, 1 knot = 1.853184 km/hr.
Thanks, but not needed as this as what they gave me.
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April 1st, 2019, 10:51 PM   #24
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Quote:
Originally Posted by helpmeddddd View Post
The midpoint of HS = (-63.5,25)
If your coordinates are correct, the midpoint of HS = (-65.5, 25).

Quote:
Originally Posted by helpmeddddd View Post
Equation of HS is y = 1/14x + 831/28
The equation of the perpendicular bisector of HS is y = -x/14 + 569/28
The equation of the perpendicular bisector of MH is y = -5/2x - 609/4

Quote:
Originally Posted by helpmeddddd View Post
making each equation = each other: 1/14x + 831/28 = -5/2x - 609/4 : x = -71
making each equation = each other: -1/14x + 569/28 = -5/2x - 609/4 : x = -1208/17 = -71.0588... (and so y = 1727/68 = 25.397...)
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April 1st, 2019, 11:50 PM   #25
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Your right, is my answer acceptable?


I did make a typo with 63.5 meant to be 65.5 can I round the answer?

Last edited by helpmeddddd; April 1st, 2019 at 11:57 PM.
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April 2nd, 2019, 10:25 AM   #26
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Quote:
Originally Posted by skipjack View Post
If your coordinates are correct, the midpoint of HS = (-65.5, 25).


The equation of the perpendicular bisector of HS is y = -x/14 + 569/28
The equation of the perpendicular bisector of MH is y = -5/2x - 609/4


making each equation = each other: -1/14x + 569/28 = -5/2x - 609/4 : x = -1208/17 = -71.0588... (and so y = 1727/68 = 25.397...)
Can I round them to like (-71.06,25.4) and how would this have an effect on the other question?

Last edited by skipjack; April 2nd, 2019 at 11:42 AM. Reason: to change final "," to "."
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April 2nd, 2019, 11:10 AM   #27
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Quote:
Originally Posted by skeeter View Post
I certainly did ... good catch.

perpendicular bisector of MS should be

$y = \dfrac{7}{4}(x+73)+22$

making the intersection coordinates approx (-71,25)

so the OP is correct

Is rounding acceptable?
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April 2nd, 2019, 11:47 AM   #28
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Whilst rounding is usually acceptable, skeeter was using the perpendicular bisector of MS, whereas you had used the perpendicular bisectors of HS and MH. The problem wasn't explained clearly enough to establish which approach is appropriate. Perhaps neither approach is appropriate.
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April 2nd, 2019, 12:00 PM   #29
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Quote:
Originally Posted by skipjack View Post
Whilst rounding is usually acceptable, skeeter was using the perpendicular bisector of MS, whereas you had used the perpendicular bisectors of HS and MH. The problem wasn't explained clearly enough to establish which approach is appropriate. Perhaps neither approach is appropriate.
Sadly I see where you're coming from, but I still have to answer this question; using HS and MH is acceptable and if MS is also, should I give both workings??

Last edited by skipjack; April 2nd, 2019 at 01:01 PM.
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