Homework

Find the real part of the complex number $z$ on the unit circle given by $z = e^{i\theta}$ and $\theta = \frac{\pi}{4}$

We are given the complex number $z$ on the unit circle:

$$z = e^{i\theta}$$

For $\theta = \frac{\pi}{4}$, we have:

$$z = e^{i\frac{\pi}{4}}$$

By Euler’s formula, $e^{i\theta} = \cos \theta + i \sin \theta$, so:

$$e^{i\frac{\pi}{4}} = \cos \frac{\pi}{4} + i \sin \frac{\pi}{4}$$

We know $\cos \frac{\pi}{4} = \sin \frac{\pi}{4} = \frac{\sqrt{2}}{2}$, thus:

$$e^{i\frac{\pi}{4}} = \frac{\sqrt{2}}{2} + i \frac{\sqrt{2}}{2}$$

Therefore, the real part of $z$ is:

$$\boxed{\frac{\sqrt{2}}{2}}$$

Find the value of tan(θ) where θ is angle on the unit circle

Consider the angle $$\theta = \frac{\pi}{4}$$ on the unit circle.

We know that $$\tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)}$$.

Since $$\sin(\frac{\pi}{4}) = \frac{\sqrt{2}}{2}$$ and $$\cos(\frac{\pi}{4}) = \frac{\sqrt{2}}{2}$$, we get:

$$\tan(\frac{\pi}{4}) = \frac{\frac{\sqrt{2}}{2}}{\frac{\sqrt{2}}{2}} = 1$$

Therefore, $$\tan(\frac{\pi}{4}) = 1$$.

What is the value of \( \sin(\frac{\pi}{6}) \), \( \cos(\frac{\pi}{6}) \), and \( \tan(\frac{\pi}{6}) \)?

$$ \sin(\frac{\pi}{6}) = \frac{1}{2} $$

$$ \cos(\frac{\pi}{6}) = \frac{\sqrt{3}}{2} $$

$$ \tan(\frac{\pi}{6}) = \frac{\sin(\frac{\pi}{6})}{\cos(\frac{\pi}{6})} = \frac{\frac{1}{2}}{\frac{\sqrt{3}}{2}} = \frac{1}{\sqrt{3}} = \frac{\sqrt{3}}{3} $$

Find the value of cos(x) and sin(x) based on the unit circle

Given $x = \frac{5\pi}{4}$, we need to find $\cos(x)$ and $\sin(x)$ using the unit circle.

Step 1: Locate the angle $\frac{5\pi}{4}$ on the unit circle. This angle is in the third quadrant.

Step 2: Determine the reference angle. The reference angle for $\frac{5\pi}{4}$ is $\frac{\pi}{4}$.

Step 3: Recall the unit circle values for $\frac{\pi}{4}$. The coordinates are $(-\frac{1}{\sqrt{2}}, -\frac{1}{\sqrt{2}})$ in the third quadrant.

Therefore, $\cos(\frac{5\pi}{4}) = -\frac{1}{\sqrt{2}}$ and $\sin(\frac{5\pi}{4}) = -\frac{1}{\sqrt{2}}$.

Find the angle θ in the interval [0, 2π) for which tan(θ) = -1

Consider the unit circle, where $ \tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)} $.
For $ \tan(\theta) = -1 $, this implies that $ \sin(\theta) = -\cos(\theta) $.
Hence, $ \theta $ must be in the second or fourth quadrant, where sine and cosine have opposite signs.
This occurs at:

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

and

$$ \theta = \frac{7\pi}{4} $$

Therefore, the solutions to the equation $ \tan(\theta) = -1 $ in the interval $ [0, 2\pi) $ are:

$$ \theta = \frac{3\pi}{4} \text{ and } \frac{7\pi}{4} $$

Find the coordinates of a point on the unit circle with an angle of \( \frac{\pi}{4} \) radians

First, we need to recall that the unit circle is a circle with a radius of 1 centered at the origin.

For an angle of $ \frac{\pi}{4} $ radians, we can use the sine and cosine functions to find the coordinates.

The x-coordinate is given by $ \cos( \frac{\pi}{4} ) = \frac{\sqrt{2}}{2} $.

The y-coordinate is given by $ \sin( \frac{\pi}{4} ) = \frac{\sqrt{2}}{2} $.

Therefore, the coordinates of the point are $$ \left( \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2} \right) $$.

Find the Value of Cosine on the Unit Circle

$$\text{Given the unit circle, we need to find the value of } \cos(\theta) \text{ where } \theta \text{ is an angle such that } 2\cos^2(\theta) + \cos(\theta) – 1 = 0.$$

$$\text{Step 1: Solve the quadratic equation} $$

$$2\cos^2(\theta) + \cos(\theta) – 1 = 0$$

$$\text{Using the quadratic formula } x = \frac{-b \pm \sqrt{b^2 – 4ac}}{2a}, \text{ where } a = 2, b = 1, \text{ and } c = -1$$

$$\cos(\theta) = \frac{-1 \pm \sqrt{1^2 – 4 \cdot 2 \cdot (-1)}}{2 \cdot 2} = \frac{-1 \pm \sqrt{1 + 8}}{4} = \frac{-1 \pm 3}{4}$$

$$\text{Thus, } \cos(\theta) = \frac{2}{4} = \frac{1}{2} \text{ or } \cos(\theta) = \frac{-4}{4} = -1.$$

$$\text{Therefore, the possible values of } \cos(\theta) \text{ are } \boxed{\frac{1}{2} \text{ and } -1}.$$

Find the cosine and sine of the angle 5π/6 using the unit circle

To find the cosine and sine of the angle $ \frac{5\pi}{6} $, we can use the unit circle. The angle $ \frac{5\pi}{6} $ is in the second quadrant, where the cosine is negative and the sine is positive.

First, find the reference angle:

$$ \text{Reference angle} = \pi – \frac{5\pi}{6} = \frac{\pi}{6} $$

For the angle $ \frac{\pi}{6} $, cosine and sine values are:

$$ \cos \left( \frac{\pi}{6} \right) = \frac{\sqrt{3}}{2} $$

$$ \sin \left( \frac{\pi}{6} \right) = \frac{1}{2} $$

Since $ \frac{5\pi}{6} $ is in the second quadrant:

$$ \cos \left( \frac{5\pi}{6} \right) = -\cos \left( \frac{\pi}{6} \right) = -\frac{\sqrt{3}}{2} $$

$$ \sin \left( \frac{5\pi}{6} \right) = \sin \left( \frac{\pi}{6} \right) = \frac{1}{2} $$

Find the sine, cosine, and tangent values for the angle π/4 on the unit circle

First, we need to recognize that the angle $\frac{\pi}{4}$ is equivalent to 45 degrees.

On the unit circle, the coordinates at $\frac{\pi}{4}$ are $(\frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2})$.

The sine value is the y-coordinate:

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

The cosine value is the x-coordinate:

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

The tangent value is the ratio of the sine and cosine values:

$$\tan(\frac{\pi}{4}) = \frac{\sin(\frac{\pi}{4})}{\cos(\frac{\pi}{4})} = 1$$

So, the sine, cosine, and tangent values for the angle $\frac{\pi}{4}$ are $\frac{\sqrt{2}}{2}$, $\frac{\sqrt{2}}{2}$, and 1, respectively.

Find the value of cos(θ) using the unit circle in the complex plane when θ = π/3

First, understand that on the unit circle, a point corresponding to an angle $\theta$ can be represented as $e^{i\theta} = \cos(\theta) + i\sin(\theta)$.

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

$e^{i\frac{\pi}{3}} = \cos\left(\frac{\pi}{3}\right) + i\sin\left(\frac{\pi}{3}\right)$.

We know that $\cos\left(\frac{\pi}{3}\right) = \frac{1}{2}$ and $\sin\left(\frac{\pi}{3}\right) = \frac{\sqrt{3}}{2}$.

Hence, $e^{i\frac{\pi}{3}} = \frac{1}{2} + i\frac{\sqrt{3}}{2}$.

So, $\cos\left(\frac{\pi}{3}\right) = \frac{1}{2}$.