What I mean is, very clearly the route to answer is direct and set to be accurate. However, it is 'considerable' still in so much 'scripted accuracy', that complexity and apparent reason (lines of working / method) could emphasise applicable rules and equivalent ratios, instead of generally demonstrating they exist to reach an auxilary simplyfiable form, which agreed is mandatory to in effect have a reasonable final answer.

Very simply, to have so much rearrangement where no particular statements are mentioned in generacy to stay alligned to operations reaching a summarisable equation (reach answer eliminate next stage possible) is example working and evident, but I personally like to draw attention in this instance to using mention (at each stage what particularly? how? does it in fact keep expanded in totality?) of rule to cover slips which are so easy when re-arranging. For example, if the answer 'accidentaly' slipped early, answer could be very distant making possible no points at all after 4/5 out of 10, if black and white (consicely) what happening and answer may be 5/6 line not 4/5 all large point question in exam only will be considered for max marks, not just a large amount, making overall significant difference to pass marks.

Just read it all below, it all works out but you have to be carefull, for example, if you where incorrect in substitutnig the terms early on you may have been operating in the wrong TR (Trig Ratio), which by the end may have been so effective as even provide something like 1/ans (a 'fluke' reciprical).

Very strong answer but there is oppotunity for 10/10 not 8/10 on an exam by just also explaining the re abbreviation happening at stage 1 2 and 3.

With regards, 

M Cover

Aiesha it is encouraging you have got so far with the question, I am researching the answer as we speak...

M Cover

Thanks

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