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Question Number 144086 by liberty last updated on 21/Jun/21
If sin t + cos  t = (2/3) then cosec t+sec t =?
$$\mathrm{If}\:\mathrm{sin}\:\mathrm{t}\:+\:\mathrm{cos}\:\:\mathrm{t}\:=\:\frac{\mathrm{2}}{\mathrm{3}}\:\mathrm{then}\:\mathrm{cosec}\:\mathrm{t}+\mathrm{sec}\:\mathrm{t}\:=? \\ $$
Answered by bobhans last updated on 21/Jun/21
⇔ 1+2sin t cos t = (4/9)  ⇒ 2sin t cos t =−(5/9)  ⇒sin t cos t =−(5/(18))  ⇔ cosec t + sec t = ((2/3)/(−5/18))                                       = −(2/3). ((18)/5)                                       = −((12)/5)
$$\Leftrightarrow\:\mathrm{1}+\mathrm{2sin}\:\mathrm{t}\:\mathrm{cos}\:\mathrm{t}\:=\:\frac{\mathrm{4}}{\mathrm{9}} \\ $$$$\Rightarrow\:\mathrm{2sin}\:\mathrm{t}\:\mathrm{cos}\:\mathrm{t}\:=−\frac{\mathrm{5}}{\mathrm{9}} \\ $$$$\Rightarrow\mathrm{sin}\:\mathrm{t}\:\mathrm{cos}\:\mathrm{t}\:=−\frac{\mathrm{5}}{\mathrm{18}} \\ $$$$\Leftrightarrow\:\mathrm{cosec}\:\mathrm{t}\:+\:\mathrm{sec}\:\mathrm{t}\:=\:\frac{\mathrm{2}/\mathrm{3}}{−\mathrm{5}/\mathrm{18}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\:−\frac{\mathrm{2}}{\mathrm{3}}.\:\frac{\mathrm{18}}{\mathrm{5}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\:−\frac{\mathrm{12}}{\mathrm{5}} \\ $$

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