Practicing Success
If $3 \sec ^2 \theta+\tan \theta=7,0^{\circ}<\theta<90^{\circ}$, then the value of $\frac{{cosec} 2 \theta+\cos \theta}{\sin 2 \theta+\cot \theta}$ is: |
$\frac{2+3 \sqrt{2}}{4}$ $\frac{3+\sqrt{2}}{2}$ $\frac{2+\sqrt{2}}{4}$ $\frac{2+\sqrt{3}}{2}$ |
$\frac{2+\sqrt{2}}{4}$ |
3 sec²θ + tanθ = 7 { we know, sec²θ - tan²θ = 1 } 3 ( 1 + tan²θ ) + tanθ = 7 3 tan²θ + tanθ - 4 = 0 3 tan²θ +4 tanθ - 3tanθ - 4 = 0 tanθ ( 3tanθ + 4 ) - 1 ( 3tanθ + 4 ) = 0 ( tanθ - 1 ). ( 3tanθ + 4 ) = 0 Either ( tanθ - 1 ) = 0 Or ( 3tanθ + 4 ) = 0 ( 3tanθ + 4 ) = 0 is not possible. So, ( tanθ - 1 ) = 0 tanθ = 1 { tan45º = 1 } Now, \(\frac{ cosec 2θ + cosθ}{ sin2θ + cotθ}\) = \(\frac{ cosec 90º + cos45º}{ sin90º + cot45º}\) = \(\frac{ 1 +1/√2}{ 1 +1 }\) = \(\frac{ √2 +1}{ 2√2 }\) = \(\frac{ 2 +√2}{ 4 }\) |