Keerthana
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यदि θ heta न्यून कोण हो और cosθ=1517cos heta=frac{15}{17}, तो cot(90θ)cot left(90^{circ}- heta ight) का मूल्य है

a

2815frac{2 sqrt{8}}{15}

b

217frac{sqrt{2}}{17}

c

815frac{8}{15}

d

8217frac{8 sqrt{2}}{17}

Answer : Option A
Explanation :
cosθ=1517secθ=1cosθ=1715cos heta=frac{15}{17} Rightarrow sec heta=frac{1}{cos heta}=frac{17}{15} cot(90θ)=tanθ=sec2θ1 herefore cot left(90^{circ}- heta ight)= an heta=sqrt{sec ^{2} heta-1} =(1715)21=2892251=sqrt{left(frac{17}{15} ight)^{2}-1}=sqrt{frac{289}{225}-1} =289225225=64225=815=sqrt{frac{289-225}{225}}=sqrt{frac{64}{225}}=frac{8}{15} Alternative:

यह देखते हुए कि cosθ=1517=bhcos heta=frac{15}{17}=frac{b}{h}

ऊँचाई =( कर्ण)2(आधार)2=sqrt{( ext { कर्ण})^{2}-( ext {आधार})^{2}}

=(17)2(15)2=64=8=sqrt{(17)^{2}-(15)^{2}}=sqrt{64}=8

cot(90θ)=tanθ= Height  Base cot left(90^{circ}- heta ight)= an heta=frac{ ext { Height }}{ ext { Base }}

=815=frac{8}{15}

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