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Trigonometry, SMB-021

  1. Express the ratio of `cos theta`  in its simplest form.  (2 marks)

  2. Hence, find the value of `theta`, correct to two decimal places.  (1 mark)

Show Answers Only
  1. `cos theta = 4/5`
  2. `theta = 36.87^@`
Show Worked Solution

i.    `text{By Pythagoras,}`

`x^2+8^2` `=10^2`  
`x^2` `=100-36`  
  `=64`  
`x` `=8`  

 
`:.cos theta = 8/10=4/5`

 

ii.   `theta` `=cos^{-1}(4/5)`  
  `=36.869…^@`  
  `=36.87^@\ text{(to 2 d.p.)}`