# Stuck on Q12b - Sine rules question AS Pure Maths

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#1

What do they mean by the answer:
"That the angles have been measured from ground level"

EDIT: SOLVED
Last edited by GogetaORvegito?; 1 year ago
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1 year ago
#2
The model, as shown in the diagram, has the base of the two triangles at ground level. Imagine instead that the angles were measured at eye height - this would not match up with the model.

Dan
Data Science, MSc @ HWU
1
#3
(Original post by Heriot-Watt University - Student Rep)
The model, as shown in the diagram, has the base of the two triangles at ground level. Imagine instead that the angles were measured at eye height - this would not match up with the model.

Dan
Data Science, MSc @ HWU
So what you are saying is that there could be a human error because of the person measuring the angles from the top of the building, relying on their eyes?
0
1 year ago
#4
This method of measuring heights is done from the ground - you look up at what you're measuring and work out the angle between the ground and that point. You then take a measurement on the ground (either to the base of the object or like the example here) and use trig to work out the height. You can measure from ground level as shown here or you can measure from a fixed point above the ground (which is probably easier than getting right down on the ground!). If you do that though you have to adjust your model to account for it, which has not been done in this example.

Dan
Data Science, MSc @ HWU
1
1 year ago
#5
hey! i would recommend accessing the solutionbank of the textbook for worked solutions to the question so you can actually understand how to do it as opposed to just having an answer from the back of the book.

you can access them for all edexcel textbooks, but here is the one for edexcel pure maths year 1:
https://www.physicsandmathstutor.com...-maths-year-1/

good luck!
1
1 year ago
#6
(Original post by GogetaORvegito?)

What do they mean by the answer:
"That the angles have been measured from ground level"
You assume that that the surveyor has measured the angle from the ground, rather than from e.g. their eye-level (which would make the angles smaller)
I've done a sketch to help visualise it http://sketchtoy.com/69289450
Last edited by laurawatt; 1 year ago
2
#7
(Original post by laurawatt)
You assume that that the surveyor has measured the angle from the ground, rather than from e.g. their eye-level (which would make the angles smaller)
I've done a sketch to help visualise it http://sketchtoy.com/69289450
OH THATS WHAT THAT MEANT. That sketch was so helpful! Thank you so much!
1
#8
(Original post by jasmeenx)
hey! i would recommend accessing the solutionbank of the textbook for worked solutions to the question so you can actually understand how to do it as opposed to just having an answer from the back of the book.

you can access them for all edexcel textbooks, but here is the one for edexcel pure maths year 1:
https://www.physicsandmathstutor.com...-maths-year-1/

good luck!
I had already checked exam solutions beforehand but thanks for bringing this information up anyway (in case I didn't know). Exam solutions was also just as vague though
0
#9
(Original post by Heriot-Watt University - Student Rep)
This method of measuring heights is done from the ground - you look up at what you're measuring and work out the angle between the ground and that point. You then take a measurement on the ground (either to the base of the object or like the example here) and use trig to work out the height. You can measure from ground level as shown here or you can measure from a fixed point above the ground (which is probably easier than getting right down on the ground!). If you do that though you have to adjust your model to account for it, which has not been done in this example.

Dan
Data Science, MSc @ HWU
Oh I understand what you mean now. Before I thought the person was measuring the angle being on the roof of the building and using super mental maths to estimate the angle on the ground LOL
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