If `tan theta = 80`, what is the value of `theta`, correct to 2 decimal places?
- `5.40°`
- `5.67°`
- `89.20°`
- `89.28°`
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If `tan theta = 80`, what is the value of `theta`, correct to 2 decimal places?
`D`
`tan theta` | `=80` |
`theta` | `=tan^(-1)80` |
`=89.28°` |
`=>D`
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i. `text{By Pythagoras,}`
`x^2+8^2` | `=17^2` | |
`x^2` | `=289-64` | |
`=225` | ||
`x` | `=15` |
`:.tan theta = 15/8`
ii. `theta` | `=tan^{-1}(15/8)` | |
`=61.927…^@` | ||
`=61.93^@\ text{(to 2 d.p.)}` |
Express `tan theta` as a fraction in its simplest form. (3 marks)
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`tan theta = (2sqrt5)/5`
`text{Let unknown side =}\ x`
`text{By Pythagoras:}`
`6^2` | `=x^2 + 4^2` | |
`x^2` | `=36-16` | |
`x` | `=sqrt20\ \ (x>0)` |
`:.tan theta` | `=4/sqrt20` | |
`= 4/(2sqrt5) xx sqrt5/sqrt5` | ||
`= (2sqrt5)/5` |
Using Pythagoras and showing your working, express `tan 30^{@}` as a fraction. (2 marks)
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`tan 30^{@} = 1/sqrt3`
`text{Let}\ \ x =\ text{unknown side}`
`text{By Pythagoras:}`
`2^2` | `=x^2 + 1^2` | |
`x^2` | `=4-1` | |
`x` | `=sqrt3\ \ (x>0)` |
`tan 30^{@} = text{opp}/text{adj} = 1/sqrt3`
Express the following as a fraction
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i. `sin theta = text{opp}/text{hyp} = 7/25`
ii. `tan theta = text{opp}/text{adj} = 7/24`
Express the following as a simplified fraction
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i. `cos theta = text{adj}/text{hyp} = 6/10 = 3/5`
ii. `tan theta = text{opp}/text{adj} = 8/6 = 4/3`
Consider the triangle shown.
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a. | `tan theta` | `= frac{8}{10}` |
`theta` | `= tan ^(-1) frac{8}{10}` | |
`= 38.659…` | ||
`= 39^@ \ text{(nearest degree)}` |
b. `text{Using Pythagoras:}`
`x` | `= sqrt{8^2 + 10^2}` |
`= 12.806…` | |
`= 12.8 \ \ text{(to 1 d.p.)}` |