If $2\sin \theta + 15 \cos^2 \theta = 7, 0^\circ < \theta < 90^\circ$ then what is the value of $\frac{3 - \tan \theta}{2 + \tan \theta}$? |
$\frac{1}{4}$ $\frac{1}{2}$ $\frac{5}{8}$ $\frac{3}{4}$ |
$\frac{1}{2}$ |
2 sinθ + 15 cos²θ = 7 { using , sin²θ + cos²θ = 1 } 2 sinθ + 15( 1 - sin²θ ) = 7 15 sin²θ - 2sinθ - 8 = 0 15 sin²θ - 12sinθ + 10sinθ - 8 = 0 3 sinθ (5 sinθ - 4 ) + 2 (5 sinθ - 4 )= 0 Either (3 sinθ + 2 )= 0 OR (5 sinθ - 4 )= 0 sinθ = - \(\frac{2}{3}\) { not possible } So , sinθ = \(\frac{4}{5}\) By using pythagoras theorem , P² + B² = H² 4² + B² = 5² B = 3 Now, \(\frac{3 - tanθ}{2 + tanθ}\) = \(\frac{3 - 4/3}{2 +4/3}\) = \(\frac{1}{2}\)
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