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प्रश्न
Write True' or False' and justify your answer the following :
The value of sin θ+cos θ is always greater than 1 .
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उत्तर
Consider the table.
| θ | 0° | 30° | 45° | 60° | 90° |
| `sin θ` | `0` | `1/2` | `1/sqrt2` | `sqrt3/2` | `1` |
| `cosθ` | `1` | `sqrt3/2` | `1/sqrt2` | `1/2` | `0` |
Here,
`sin 90°+cos 90°=1+0=1` Which is not greater than 1 Therefore, the given statement is false,
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cotθ + tanθ = cosecθ × secθ
Activity: L.H.S. = cotθ + tanθ
= `cosθ/sinθ + square/cosθ`
= `(square + sin^2theta)/(sinθ xx cosθ)`
= `1/(sinθ xx cosθ)` ....... ∵ `square`
= `1/sinθ xx 1/cosθ`
= `square xx secθ`
∴ L.H.S. = R.H.S.
