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    http://www.ocr.org.uk/Images/136129-...hematics-2.pdf

    7 a) i) and ii) I honestly haven't come across this type of question before. Well I worked out part i) as you can draw a right angle triangle but I have no idea how to get an exact answer for part ii)- can somebody help me out?
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    What do you know about obtuse angles?
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    If you draw the triangle in a quadrant diagram, in or order for the angle to be obtuse it has to be drawn in the second or third quadrant, as the angle is calculated from the first quadrant; compare sides like you did in the first part and consider where cosine is positive and negative.

    Alternatively you can use a trig identity.
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    All I know about obtuse angles is that they are greater than 90 degrees. Anyway I'm just going to hope it doesn't come up and go to bed- I'm really tired.
 
 
 
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