Unit Overview
P1 - Surveying Equipment
P2 - Drawing Your Plan
P3 - Levelling Equipment
P4 - Height Profile
P5 - Theodolites
P6 - Measuring Angles
P7 - Setting Out Terminology
P8 - Setting out Practical
M1
M2
M3 - Setting Up Profile Boards
D1
D2
D3

P6 - Carry out angular measurements, using appropriate equipment, and calculations

Criteria

carry out angular measurements, using appropriate equipment, and calculations

 

Task

Your tutor has asked you to carry out a range of tasks:

 

  1. Record the height of the flood lights in the school playground.
  2. Record the height of the school buildings
  3. Calculate the length of the of wall where direct access is not available

 

 

Unlike P2 and P4 you need only carry out the calculations there is no requirement for a drawing at this point (other than updating the school plan).

 

You should record all your calculations as evidence for this task.

 

You will need to calculate the heights by using trigonometry, below is an example of using Tan to calculate the height of a building.

 

heights using tanWe can measure a set distance back from the building, in this case 25m.

We then use the theodolite to calculate the angle from the horizontal plane to the top of the building, in this case 27 degrees.

 

We can then carry out the following calculation (don't forget about turning your phone on it's side for the tan function).

 

Remember SOHCAHTOA from maths, all you need to remember is the TOA bit for now, which is Tan = Opposite over the Adjacent.

 

So without going into how to balance the equation, this is all you need to do:

 

  1. Find the tan of 27 using the tan function on your calculator (its .509)

  2. Multiply this by the length of 25m and you get a height of 12.72m.

  3. You can check the accuracy of your readings by taking them from different distances.

 

Don't forget you will need to add the height of the theodolite to the height you have calculated, in this case 1.6m.

 

So the final height of the building is 12.72m + 1.6m = 14.325