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-   -   A geometry time question (http://mymathforum.com/geometry/346131-geometry-time-question.html)

helpmeddddd April 1st, 2019 02:02 PM

A geometry time question
 
If a rescue craft is launched from Miami and can travel with a maximum speed of 35 knots, how long should it take to reach the crash site? Note: 1 knot = 1.852 km/hr. The approximate distance in this region for latitude of 1° = 111 km and longitude 1° = 100 km.

Let's suppose the coordinates is (-71,25) Miami is (−80,26).

Have I solved it?? 13hrs 59m 33s???

skeeter April 1st, 2019 02:15 PM

assuming your coordinates are (longitude,latitude), I get about 10 second less time.

helpmeddddd April 1st, 2019 02:25 PM

Yeah they are longitude, latitude. What process did you use to solve I'm interested! if you could please reply thanks.


I personally multiplied both longitude coordinates by 100 and the latitude by 111, getting -80x100, -71x100, 25x111, 26x111, then I put them into the square root (x2-x1)squared + (y2-y1)squared to get 907km, then I used the time = d/s to get my answer.

skeeter April 1st, 2019 02:45 PM

$t = \dfrac{\sqrt{900^2 + 111^2}}{35 \cdot 1.852} = 13.989... \, hrs$

$(0.989... \, hrs)(60 \, min/hr) = 59.388... \, min$

$(0.388... \, min)(60 \, sec/min) \approx 23.3 \, sec$

13 hrs 59 min 23 sec

helpmeddddd April 1st, 2019 02:47 PM

maybe my calculations are wrong ??

skeeter April 1st, 2019 02:51 PM

Quote:

Originally Posted by helpmeddddd (Post 607704)
I see you are multiplying by knots (35) whereas I'm multiplying by 64.82km/hr

1 kt = 1.852 km/hr $\implies$ 35 kts = 35(1.852) km/hr = 64.82 km/hr

same same

helpmeddddd April 1st, 2019 02:54 PM

Yeah you are right

is there any mathematical statement I can use to go alongside this?

skeeter April 1st, 2019 02:58 PM

Quote:

Originally Posted by helpmeddddd (Post 607706)
Yeah you are right

is there any mathematical statement I can use to go alongside this?

what do you mean? it's just a problem involving $time = \dfrac{distance}{speed}$ with a couple of unit conversions

helpmeddddd April 1st, 2019 03:05 PM

Yeah, I don't know. Could you be please check I've correctly solved my other problem on another thread. I'll just put it in this box.


question A plane's emergency beacon goes off, its approx position is at a place equidistant from Miami and San Juan and on altitude from Miami, in the Bermuda triangle.

Locate where the plane has crashed

M(−80,26), H(−65,32), S(−66,18).

skeeter April 1st, 2019 03:31 PM

Quote:

Originally Posted by helpmeddddd (Post 607708)
Yeah, I don't know. Could you be please check I've correctly solved my other problem on another thread. I'll just put it in this box.


question A plane's emergency beacon goes off, its approx position is at a place equidistant from Miami and San Juan and on altitude from Miami, in the Bermuda triangle.

Locate where the plane has crashed

M(−80,26), H(−65,32), S(−66,18).

M is probably Miami, S is probably San Juan ... what does H represent?


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