Chapter 3: Problem 10
Evaluate each statement given in exercises \(6-10\). $$ \sin \left(\frac{3 \pi}{2}\right) $$
Short Answer
Expert verified
\( \sin \left(\frac{3\pi}{2}\right) = -1 \).
Step by step solution
01
Understanding the Expression
We are given the expression \( \sin \left(\frac{3\pi}{2}\right) \). This asks us to find the sine of \( \frac{3\pi}{2} \), which is an angle measured in radians.
02
Identify the Angle on the Unit Circle
The angle \( \frac{3\pi}{2} \) in radians is equal to 270 degrees. On the unit circle, this angle corresponds to the negative y-axis.
03
Sine Value of the Angle
On the unit circle, the sine of an angle corresponds to the y-coordinate of the point where the terminal side of the angle intersects the circle. For \( \frac{3\pi}{2} \), this point is (0, -1).
04
Conclusion
Since the sine of an angle is the y-coordinate of the corresponding point on the unit circle, \( \sin \left(\frac{3\pi}{2}\right) = -1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Unit Circle
The unit circle is a fundamental concept in trigonometry, providing a geometric interpretation of trigonometric functions. It is a circle with a radius of one unit centered at the origin of a coordinate plane.
- Every point on the unit circle is determined by an angle measured from the positive x-axis. This angle can be measured in either degrees or radians.
- A point on the unit circle can be expressed in terms of coordinates \((x, y)\), which correspond to \((\cos(\theta), \sin(\theta))\) for an angle \(\theta\).
- The x-coordinate represents the cosine of the angle, while the y-coordinate represents the sine of the angle.
Angle Measurement
Angle measurement is crucial in trigonometry as it tells us how much we have rotated around a circle. There are two main units for angle measurement: degrees and radians.
- Degrees divide a circle into 360 equal parts. Each part is one degree \((1^\circ)\).
- Radians, however, relate the angle to the arc length of a circle. One radian is the angle formed when the arc length equals the radius of the circle.
- The full circle, therefore, measures \(2\pi\) radians or 360 degrees, making conversion between the two units possible through the equivalence \(\pi\) radians = 180 degrees.
Trigonometric Functions
Trigonometric functions describe relationships between the angles and sides of triangles. They extend these relationships to the unit circle and are pivotal in various scientific fields.
- The primary trigonometric functions are sine \((\sin)\), cosine \((\cos)\), and tangent \((\tan)\).
- Sine of an angle in a right triangle is the ratio of the length of the opposite side to the hypotenuse. On the unit circle, this translates to the y-coordinate of the point associated with the angle.
- Cosine corresponds to the x-coordinate of the same point, and tangent is the ratio of sine to cosine.