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If cosecθ = 1 9 20 , show that 1 − sin θ + cos θ 1 + sin θ + cos θ = 3 7 - Mathematics

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प्रश्न

If cosecθ = `1(9)/(20)`, show that `(1 - sinθ + cosθ)/(1 + sinθ + cosθ) = (3)/(7)`

योग

उत्तर

cosecθ = `1(9)/(20) = (29)/(20)`

sinθ = `(1)/(cosecθ) = (20)/(29) = "Perpendicular"/"Hypotenuse"`
Base
= `sqrt(("Hypotenuse")^2 - ("Perpendicular")^2`
= `sqrt((29)^2 - (20)^2`
= `sqrt(841 - 400)`
= `sqrt(441)`
= 21

cosθ = `"Base"/"Hypotenuse" = (21)/(29)`

To show: `(1 - sinθ + cosθ)/(1 + sinθ + cosθ) = (3)/(7)`

`(1 - sinθ + cosθ)/(1 + sinθ + cosθ)`

= `(1 - 20/29 + 21/29)/(1 + 20/29 + 21/29)`

= `(29 - 20 + 21)/(29 + 20 + 21)`

= `(30)/(70)`

= `(3)/(7)`.

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अध्याय 26: Trigonometrical Ratios - Exercise 26.1

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फ्रैंक Mathematics [English] Class 9 ICSE
अध्याय 26 Trigonometrical Ratios
Exercise 26.1 | Q 31
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