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The radius of the given circle intersects the unit circle at [tex]\left(\frac{3}{5}, \frac{4}{5}\right)[/tex]. What is the approximate value of the angle?

A. 53.1 degrees
B. 0.6 radians
C. 36.9 degrees
D. 1.0 radians

Answer :

To solve the problem and find the approximate value of the angle, we are given that the radius intersects the unit circle at the point [tex]\(\left(\frac{3}{5}, \frac{4}{5}\right)\)[/tex].

1. Understand the Geometry: The point [tex]\(\left(\frac{3}{5}, \frac{4}{5}\right)\)[/tex] is on the unit circle, which means that it forms a right-angled triangle with the x-axis and the line (radius) from the origin (0, 0) to [tex]\(\left(\frac{3}{5}, \frac{4}{5}\right)\)[/tex]. The radius of the unit circle is 1.

2. Identify Triangle Sides:
- The x-coordinate, [tex]\(\frac{3}{5}\)[/tex], represents the length of the base (adjacent side to the angle) of this right triangle.
- The y-coordinate, [tex]\(\frac{4}{5}\)[/tex], represents the length of the height (opposite side to the angle) of the triangle.
- The hypotenuse is the radius, which is 1, as it is the unit circle.

3. Calculate the Angle in Radians:
- We can use the cosine function to find the angle [tex]\(\theta\)[/tex], because [tex]\(\cos(\text{angle}) = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{3}{5}\)[/tex].
- Therefore, [tex]\(\theta = \cos^{-1}\left(\frac{3}{5}\right)\)[/tex].

4. Convert to Degrees:
- Once you have the angle in radians, convert it to degrees using the conversion factor: [tex]\(1 \text{ radian} = \frac{180}{\pi} \text{ degrees}\)[/tex].

5. Approximate the Angle:
- The angle we've calculated is approximately 53.1 degrees in its degree form.
- In radians, it rounds to approximately 0.9 radians.

In conclusion, the approximate value of the angle described by the given point on the unit circle is 53.1 degrees or 0.9 radians.

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