Homework

Find the angle corresponding to the cosine value of -2/3 on the unit circle

To find the angle corresponding to the cosine value of $-\frac{2}{3}$ on the unit circle, we start with the definition of cosine in terms of the unit circle.

The cosine of an angle is the x-coordinate of the point on the unit circle. Therefore, we need to determine the angles whose x-coordinate is $-\frac{2}{3}$.

Since cosine is negative in the second and third quadrants, the angles we are looking for are in these quadrants.

1. First angle: Let θ be the angle in the second quadrant.

$$\theta = \cos^{-1} \left( -\frac{2}{3} \right) $$

Using a calculator, we find that

$$\theta \approx 131.81 ^\circ $$

2. Second angle: In the third quadrant, the reference angle is the same, but we add 180 degrees.

$$\theta = 180 ^\circ + 48.19 ^\circ = 228.19 ^\circ$$

Therefore, the two angles are approximately 131.81° and 228.19°.

Given an angle θ in the unit circle, find the secant of θ, where θ is in the interval [0, 2π] Provide your answer in three different forms

To find the secant of angle $\theta$, we start by recalling that $\sec(\theta) = \frac{1}{\cos(\theta)}$.

Let’s consider an angle $\theta = \frac{5\pi}{4}$.

First, we find $\cos(\frac{5\pi}{4})$:

$$\cos(\frac{5\pi}{4}) = -\frac{\sqrt{2}}{2}$$

Thus, $$\sec(\frac{5\pi}{4}) = \frac{1}{-\frac{\sqrt{2}}{2}} = -\sqrt{2}$$

Therefore, $$\sec(\frac{5\pi}{4}) = -\sqrt{2}$$

Find the sin, cos, and tan values for the angle θ = 45° in the unit circle

For the angle $ \theta = 45° $ in the unit circle:

The coordinates are $ ( \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2} ) $.

Thus, $$ \sin 45° = \frac{\sqrt{2}}{2} $$

$$ \cos 45° = \frac{\sqrt{2}}{2} $$

$$ \tan 45° = 1 $$

Find the value of cotangent of an angle on the unit circle

To find the value of $\cot(\theta)$, we need to use the coordinates of the angle on the unit circle. Let $\theta$ be an angle in the unit circle with coordinates $(\cos(\theta), \sin(\theta))$.

The formula for cotangent is given by:

$$\cot(\theta) = \frac{1}{\tan(\theta)} = \frac{\cos(\theta)}{\sin(\theta)}$$

If $\theta = \frac{\pi}{4}$, then $\cos(\frac{\pi}{4}) = \sin(\frac{\pi}{4}) = \frac{\sqrt{2}}{2}$.

Thus,

$$\cot(\frac{\pi}{4}) = \frac{\cos(\frac{\pi}{4})}{\sin(\frac{\pi}{4})} = \frac{\frac{\sqrt{2}}{2}}{\frac{\sqrt{2}}{2}} = 1$$

Find the coordinates of point P on the unit circle

Given a point P on the unit circle at an angle $\theta = \frac{\pi}{3}$ radians, we need to find its coordinates.

The coordinates of a point on the unit circle are given by $ (\cos \theta, \sin \theta) $.

So, we will use the values of cosine and sine for $\theta = \frac{\pi}{3}$.

$$ \cos \frac{\pi}{3} = \frac{1}{2} $$

$$ \sin \frac{\pi}{3} = \frac{\sqrt{3}}{2} $$

Therefore, the coordinates of point P are:

$$ \left( \frac{1}{2}, \frac{\sqrt{3}}{2} \right) $$

Find the general solutions for the equation cos(θ) = 05 on the unit circle

To solve the equation $\cos(\theta) = 0.5$, we need to find the angles on the unit circle where the cosine value equals $0.5$.

First, we know that $\cos(\theta) = 0.5$ at $\theta = \frac{\pi}{3}$ and $\theta = -\frac{\pi}{3}$.

In general, these solutions can be expressed as:

$$ \theta = \frac{\pi}{3} + 2k\pi $$

or

$$ \theta = -\frac{\pi}{3} + 2k\pi $$

where $k$ is any integer.

Find the sine, cosine, and tangent values for an angle of 45 degrees on the unit circle

$$\text{For an angle of } 45^\circ \text{ on the unit circle:}$$

$$\sin(45^\circ) = \frac{1}{\sqrt{2}} = \frac{\sqrt{2}}{2}$$

$$\cos(45^\circ) = \frac{1}{\sqrt{2}} = \frac{\sqrt{2}}{2}$$

$$\tan(45^\circ) = \frac{\sin(45^\circ)}{\cos(45^\circ)} = 1$$

Fill in the unit circle with the corresponding coordinates for the angle of 45 degrees

To find the coordinates of the angle $45^\circ$ on the unit circle, we use the fact that at $45^\circ$, both the $x$-coordinate and $y$-coordinate are equal.

In the unit circle, this coordinate is found by:

$x = \cos(45^\circ) = \frac{\sqrt{2}}{2}$

$y = \sin(45^\circ) = \frac{\sqrt{2}}{2}$

Thus, the coordinates for the angle $45^\circ$ are:

$$ \left( \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2} \right) $$

Given the unit circle and the periodic function $f(\theta) = \sin(\theta)$, find the values of $\theta$ for which $\sin(\theta) = \frac{\sqrt{2}}{2}$ in the interval $[0, 2\pi)$ Provide a detailed solution

Consider the given equation:

$$\sin(\theta) = \frac{\sqrt{2}}{2}$$

We know that $$\sin(\theta) = \frac{\sqrt{2}}{2}$$ at $$\theta = \frac{\pi}{4} + 2n\pi$$ and $$\theta = \frac{3\pi}{4} + 2n\pi$$ for any integer $$n$$.

To find the solutions in the interval $$[0, 2\pi)$$, we consider:

$$\theta = \frac{\pi}{4}$$

$$\theta = \frac{3\pi}{4}$$

Thus, the solutions are:

$$\theta = \frac{\pi}{4}, \frac{3\pi}{4}$$

Find the Sine and Cosine of an Angle Given in a Flipped Unit Circle Problem

Given an angle $\theta$ in the flipped unit circle, where the x-values represent the sine of the angle and the y-values represent the cosine of the angle, find the sine and cosine of $\theta = \frac{5\pi}{4}$.

First, note that $\theta = \frac{5\pi}{4}$ is in the third quadrant. In the standard unit circle, $\sin(\frac{5\pi}{4}) = -\frac{1}{\sqrt{2}}$ and $\cos(\frac{5\pi}{4}) = -\frac{1}{\sqrt{2}}$.

Since the roles of sine and cosine are flipped, the sine of $\theta$ will be the x-coordinate, and the cosine of $\theta$ will be the y-coordinate.

Hence, the sine of $\theta = \frac{5\pi}{4}$ is $-\frac{1}{\sqrt{2}}$, and the cosine of $\theta = \frac{5\pi}{4}$ is $-\frac{1}{\sqrt{2}}$.