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Unformatted text preview: ines can cope with every situtation. So, in the interests of simplicity, cosines have not been
specifically mentioned here in the early work. Of course they can always be used if wished.
Before applying trigonometry to 'real' problems, some thought must be given to the background
knowledge needed. The most commonly needed knowledge concerns angles of elevation and depression,
together with compass bearings and directions. Then there is the usual assumption that the ground is
level and horizontal, and walls and poles etc are vertical.
In problems, dimensions must always be borne in mind of course, and units must be consistent.
But the usual problems set for pupils do not have inconsistencies in them, and there are none here. (Try
putting in a problem about finding the angle of descent of an aeroplane which loses 1000 metres of
height along a glidepath of 5 kilometres!) In the graphical work given here, units are not stated at all.
Keep in mind there is an order of difficulty for pupils working with trigratios. Finding...
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This document was uploaded on 03/01/2014.
 Spring '14

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