Soru

Zorluk: OrtaTrigonometric Ratios and Identities

In a right triangle, the two acute angles are θ\theta and ϕ\phi. If sin(θ)=725\sin(\theta) = \frac{7}{25} and cos(ϕ)=k50\cos(\phi) = \frac{k}{50}, what is the value of kk?

Cevap: 14

Cevap

14
In any right triangle, the two acute angles, θ\theta and ϕ\phi, must sum to 9090^\circ. The cofunction trigonometric identity states that sin(θ)=cos(90θ)=cos(ϕ)\sin(\theta) = \cos(90^\circ - \theta) = \cos(\phi). Therefore, we can equate the two given values: 725=k50\frac{7}{25} = \frac{k}{50}. Solving this equation for kk gives k=7×5025=14k = \frac{7 \times 50}{25} = 14.

Adım Adım Çözüm

1
Determine the relationship between the two acute angles in a right triangle.
θ+ϕ=90\theta + \phi = 90^\circ
Since the sum of the angles in any triangle is 180180^\circ and a right triangle has one 9090^\circ angle, the sum of the other two acute angles must be 9090^\circ.
2
Apply the cofunction trigonometric identity for complementary angles.
sin(θ)=cos(ϕ)\sin(\theta) = \cos(\phi)
The sine of an acute angle is always equal to the cosine of its complement.
3
Equate the given expressions and solve for kk.
725=k50    k=14\frac{7}{25} = \frac{k}{50} \implies k = 14
Substitute the given values into the identity and multiply both sides by 5050 to isolate kk.

Anahtar Kavram

Cofunction identities for complementary angles in a right triangle
Bu soruyu puanla