Question

(1) tan (cos-1 x) = sin(tan-12)

JEE/Engineering Exams

Maths

Solution

184

4.0 (1 ratings)

( tan left(cos ^{-1} xright)=sin left(tan ^{-1} 2right) ) ( tan left(tan ^{-1} frac{sqrt{1-x^{2}}}{x}right)=sin left(sin ^{-1} frac{2}{sqrt{5}}right) quad frac{1}{sqrt{5}} x ) ( frac{sqrt{1-x^{2}}}{x}=frac{2}{sqrt{5}}left(begin{array}{l}text { squaring } text { both sides }end{array}right) ) ( pi ) ( frac{1-x^{2}}{x^{2}}=frac{4}{5} ) ( 5-5 x^{2}=4 x^{2} ) ( 5=9 x^{2} quadleft[text { Any } x=frac{3}{sqrt{5}}right] ) ( x=sqrt{frac{9}{5}} )