In the right triangle [tex]\(XYZ\)[/tex], [tex]\(\angle X\)[/tex] and [tex]\(\angle Z\)[/tex] are complementary angles, and [tex]\(\cos (\angle X)\)[/tex] is [tex]\(\frac{9}{11}\)[/tex]. What is [tex]\(\sin (\angle Z)\)[/tex]?

A. [tex]\(\frac{\sqrt{20}}{11}\)[/tex]

B. [tex]\(\frac{11}{9}\)[/tex]

C. [tex]\(\frac{\sqrt{20}}{9}\)[/tex]

D. [tex]\(\frac{9}{11}\)[/tex]



Answer :

To solve the problem, follow these steps:

1. Understand the relationship between the angles in a right triangle:
- In a right triangle, the two non-right angles are complementary, meaning that their measures add up to 90 degrees.

2. Use the complementary angle property:
- If [tex]\(\angle X\)[/tex] and [tex]\(\angle Z\)[/tex] are complementary angles, then [tex]\(\cos(X) = \sin(Z)\)[/tex]. This is due to the fact that [tex]\(\cos(\theta) = \sin(90^\circ - \theta)\)[/tex], where [tex]\(\theta\)[/tex] is an angle in the triangle.

3. Given information:
- We know [tex]\(\cos(X) = \frac{9}{11}\)[/tex].

4. Apply the trigonometric identity:
- Since [tex]\(\cos(X) = \sin(Z)\)[/tex] and we are given [tex]\(\cos(X) = \frac{9}{11}\)[/tex], it follows directly that [tex]\(\sin(Z) = \frac{9}{11}\)[/tex].

Thus, the value of [tex]\(\sin(Z)\)[/tex] is [tex]\(\frac{9}{11}\)[/tex].

So, the correct answer is

D. [tex]\(\frac{9}{11}\)[/tex].