Practicing Success
If $\frac{\sin ^2 \theta}{\tan ^2 \theta-\sin ^2 \theta}=5, \theta$ is an acute angle, then the value of $\frac{24 \sin ^2 \theta-15 \sec ^2 \theta}{6{cosec}^2 \theta-7 \cot ^2 \theta}$ is: |
-2 2 -14 14 |
-14 |
\(\frac{sin²θ}{tan²θ - sin²θ }\) = 5 \(\frac{sin²θ}{sin²θ/cos²θ - sin²θ }\) = 5 \(\frac{sin²θ}{sin²θ.sec²θ - sin²θ }\) = 5 \(\frac{sin²θ}{sin²θ(sec²θ -1) }\) = 5 { using , sec²θ - tan²θ = 1 } \(\frac{sin²θ}{sin²θ(tan²θ) }\) = 5 cot²θ = 5 cotθ = \(\frac{√5 }{1 }\) { We know, cotθ = \(\frac{B }{P}\) } By using pythagoras theorem , P² + B² = H² 1² + 5 = H² H = √6 Now, \(\frac{24sin²θ - 15sec²θ}{6cosec²θ - 7cot²θ }\) = \(\frac{24×1/6 - 15×6/5}{6×6/1 - 7×5 }\) = \(\frac{4 - 18}{36 - 35 }\) = -14 |