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What you need to know
What you need to know:
In the higher course, the rules of standard trigonometry (SOHCAHTOA and Pythagoras) are extended into the 3rd dimension. This does not require any new formulae, and is not all that much harder than working with trigonometry in 2D. Typically, it involves using trigonometry to determine a side-length/angle, which then allows us to use our tools of trigonometry with that side-length/angle to find new information. For example, consider the following diagram.
This is quite a common question format. You may be asked to find the length of side AD, and to do so you would have to first find the length AC using trigonometry, and then further use either SOHCAHTOA, if you’re given the angle DAC, or Pythagoras, if you’re given the side-length CD, to find the length of AD. Nothing new has been done here, it’s mostly a matter of understanding the 3-dimensional picture, and then knowing how to apply our familiar rules of trigonometry.
Students often struggle to visualise the 3D Pythagoras and Trigonometry questions and teachers sometimes find it difficult to make up questions on the spot unless you are a geometrical drawing specialist, so finding excellent resources for these topics is essential. Take a look at our 3D Pythag questions and 3D Trigonometry resources and see what you find helpful.
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