Practicing Success
If $2 \sin \theta+15 \cos ^2 \theta=7,0^{\circ}<\theta<90^{\circ}$, then $\tan \theta+\cos \theta+\sec \theta=$ |
$3 \frac{3}{5}$ 3 $3 \frac{4}{5}$ 4 |
$3 \frac{3}{5}$ |
2 sinθ + 15 cos²θ = 7 { sin²θ + cos²θ = 1 } 2 sinθ + 15 ( 1 - sin²θ) = 7 2 sinθ + 15 ( 1 - sin²θ) = 7 15 sin²θ - 2 sinθ - 8 = 0 15 sin²θ - 12 sinθ + 10 sinθ - 8 = 0 3 sinθ (5 sinθ - 4) + 2 ( 5 sinθ - 4) = 0 (3 sinθ + 2) . ( 5 sinθ - 4) = 0 Either (3 sinθ + 2)= 0 or ( 5 sinθ - 4) = 0 (3 sinθ + 2)= 0 is not possible. So, ( 5 sinθ - 4) = 0 sinθ = \(\frac{4}{5}\) { sinθ = \(\frac{P}{H}\) } By using pythagoras theorem, P² + B² = H² 4² + B² = 5² B = 3 Now, tanθ + cosθ + secθ = \(\frac{P}{B}\) + \(\frac{B}{H}\) + \(\frac{H}{B}\) = \(\frac{4}{3}\) + \(\frac{3}{5}\) + \(\frac{5}{3}\) = \(\frac{20 + 9 + 25}{15}\) = 3\(\frac{ 3}{5}\) |