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Zorluk: OrtaBasic Trigonometric Ratios, Special Angles, and Identities

If θ\theta is an acute angle such that tanθ=2\tan \theta = 2, calculate the exact numerical value of 3sinθ+cosθsinθ+2cosθ\frac{3\sin \theta + \cos \theta}{\sin \theta + 2\cos \theta}.

Cevap: 1.75

Cevap

The exact numerical value of the trigonometric expression is 1.75.
Dividing every term in the expression by cosθ\cos \theta converts sinθ\sin \theta terms into tanθ\tan \theta. The quotient becomes 3tanθ+1tanθ+2\frac{3\tan \theta + 1}{\tan \theta + 2}. Substituting tanθ=2\tan \theta = 2 gives 3(2)+12+2=74=1.75\frac{3(2) + 1}{2 + 2} = \frac{7}{4} = 1.75.

Adım Adım Çözüm

1
Divide numerator and denominator by cosθ\cos \theta
The expression becomes 3(sinθcosθ)+1sinθcosθ+2=3tanθ+1tanθ+2\frac{3\left(\frac{\sin \theta}{\cos \theta}\right) + 1}{\frac{\sin \theta}{\cos \theta} + 2} = \frac{3\tan \theta + 1}{\tan \theta + 2}.
Using the trigonometric identity tanθ=sinθcosθ\tan \theta = \frac{\sin \theta}{\cos \theta} simplifies the calculation without needing to evaluate the hypotenuse.
2
Substitute tanθ=2\tan \theta = 2
3(2)+12+2=74\frac{3(2) + 1}{2 + 2} = \frac{7}{4}
Replace tanθ\tan \theta with its given numerical value of 2.
3
Convert fraction to decimal
1.75
Decimal representation of the exact fraction 74\frac{7}{4}.

Anahtar Kavram

Basic Trigonometric Ratios and Quotient Identity
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