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Trigonometry, SMB-013

Using Pythagoras and showing your working, express `cos 30^{@}` as a fraction.  (2 marks)

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`cos 30^{@} = sqrt3/2`

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`text{Let}\ \ x =\ text{unknown side}`

`text{By Pythagoras:}`

`2^2` `=x^2 + 1^2`  
`x^2` `=4-1`  
`x` `=sqrt3\ \ (x>0)`  

 
`cos 30^{@} = text{adj}/text{hyp} = sqrt3/2`