SSC Sample Paper Mock Test-13 SSC CGL Tear-II Paper-1

  • question_answer
    If   \[3\cos x=5\sin x,\] then   the   value   of \[\frac{5\sin x-2{{\sec }^{3}}x+2\cos x}{2\sin x+2{{\sec }^{3}}x-2\cos x}\] is

    A)  \[\frac{361}{2397}\]

    B)  \[\frac{271}{979}\]

    C)  \[\frac{541}{979}\]

    D)  \[\frac{127}{979}\]

    Correct Answer: B

    Solution :

    As, \[3\cos x=5\sin x\]\[\Rightarrow \]\[\frac{\sin x}{\cos x}=\frac{3}{5}\]\[\Rightarrow \]\[\tan x=\frac{3}{5}\] \[\frac{5\sin x-2{{\sec }^{3}}x+2\cos x}{2\sin x+2{{\sec }^{3}}x-2\cos x}\] On dividing numerator and denominator by cos x, we get \[\frac{5\tan x-2{{\sec }^{4}}x+2}{5\tan x+2{{\sec }^{3}}x-2}\] \[=\frac{5\tan x-2\,\,{{(1+{{\tan }^{2}}x)}^{2}}+2}{5\tan x+2\,\,{{(1+{{\tan }^{2}}x)}^{2}}-2}\] \[=\frac{5\times \frac{3}{5}-2{{\left( 1+\frac{9}{25} \right)}^{2}}+2}{5\times \frac{3}{5}+2{{\left( 1+\frac{9}{25} \right)}^{2}}-2}=\frac{3+2-2\times \frac{1156}{625}}{3-2+2\times \frac{1156}{625}}\] \[=\frac{3125-2312}{625+2312}=\frac{813}{2937}=\frac{271}{979}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner