Homework

Calculate the value of tan(4π/3) using the unit circle

To calculate $\tan\left(\frac{4\pi}{3}\right)$, we start by locating the angle $\frac{4\pi}{3}$ on the unit circle.

The angle $\frac{4\pi}{3}$ radians is equivalent to $240^\circ$.

This angle lies in the third quadrant where both sine and cosine are negative.

Using the unit circle, we find the coordinates of the point at $240^\circ$: $(\cos 240^\circ, \sin 240^\circ) = \left( -\frac{1}{2}, -\frac{\sqrt{3}}{2} \right)$.

The tangent of an angle is given by the ratio of the sine to the cosine:

$$\tan\left(\frac{4\pi}{3}\right) = \frac{\sin 240^\circ}{\cos 240^\circ} = \frac{-\frac{\sqrt{3}}{2}}{-\frac{1}{2}} = \sqrt{3}.$$

Find the value of \( \cot(\theta) \) when \( \theta = \frac{\pi}{4} \) on the unit circle

Given:

\( \theta = \frac{\pi}{4} \)

On the unit circle, the coordinates for \( \theta = \frac{\pi}{4} \) are:

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

\( \cot(\theta) = \frac{\cos(\theta)}{\sin(\theta)} \)

Substituting the values:

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

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

Find the tangent of 45 degrees using the unit circle

To find the tangent of 45 degrees using the unit circle, we first locate the point corresponding to 45 degrees on the circle. The coordinates of this point are $(\frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2})$.

Recall that the tangent function is defined as the ratio of the y-coordinate to the x-coordinate:

$$\tan(45^\circ) = \frac{\text{y-coordinate}}{\text{x-coordinate}} = \frac{\frac{\sqrt{2}}{2}}{\frac{\sqrt{2}}{2}} = 1$$

Therefore, $$\tan(45^\circ) = 1$$.

Find the coordinates of points on the unit circle corresponding to a given angle in a flipped configuration

Given a unit circle, we need to find the coordinates of points corresponding to the angle $\theta = \frac{5\pi}{4}$, but with the configuration flipped over the x-axis.

In the standard unit circle, the point corresponding to $\theta = \frac{5\pi}{4}$ is:

$$\left(\cos \frac{5\pi}{4}, \sin \frac{5\pi}{4}\right)$$

Using the trigonometric values:

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

Since the configuration is flipped over the x-axis, we change the sign of the y-coordinate:

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

Thus, the coordinates are:

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

Find the sine and cosine of the angle \(\theta\) when \(\theta = \frac{\pi}{6}\)

To find the sine and cosine of the angle $\theta$ when $\theta = \frac{\pi}{6}$, we can use the unit circle.

The angle $\frac{\pi}{6}$ radians corresponds to 30 degrees.

On the unit circle, the coordinates of the point at angle $\frac{\pi}{6}$ are:

$$\left(\cos\left(\frac{\pi}{6}\right), \sin\left(\frac{\pi}{6}\right)\right)$$

From trigonometric values:

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

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

Therefore, the sine and cosine of the angle $\theta$ when $\theta = \frac{\pi}{6}$ are given by:

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

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

Given a unit circle centered at the origin, but flipped in a non-standard way such that the positive x-axis points downwards and the positive y-axis points to the left, find the coordinates of the point corresponding to an angle of 5π/6 radians

To solve this problem, we first need to understand the transformation of the coordinate system.

In the standard unit circle, an angle of $\frac{5\pi}{6}$ radians would correspond to the point $(-\cos(\frac{\pi}{6}), \sin(\frac{\pi}{6}))$.

Therefore, in the standard unit circle, the coordinates would be:

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

Now, since the unit circle is flipped such that the positive x-axis points downwards and the positive y-axis points to the left, we need to adjust these coordinates accordingly:

1. The x-coordinate will become the negative of the original y-coordinate.

2. The y-coordinate will become the negative of the original x-coordinate.

Thus, the transformed coordinates are:

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

which simplifies to:

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

Find the value of cos(θ) on the unit circle for a given θ and determine the exact coordinates of the corresponding point

Let’s consider the angle $ \theta = \frac{7\pi}{6}$.

First, we determine the reference angle. Since $\frac{7\pi}{6}$ is in the third quadrant, we find the reference angle by subtracting $\pi$:

$$ \theta_{ref} = \frac{7\pi}{6} – \pi = \frac{7\pi}{6} – \frac{6\pi}{6} = \frac{\pi}{6} $$

The cosine of the reference angle $\frac{\pi}{6}$ is $\frac{\sqrt{3}}{2}$, but since we are in the third quadrant, the cosine value is negative:

$$ \cos\left(\frac{7\pi}{6}\right) = -\frac{\sqrt{3}}{2} $$

The exact coordinates of the point on the unit circle corresponding to $\theta = \frac{7\pi}{6}$ are:

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

Find the coordinates of the point where the line y = 2x intersects the unit circle

First, let’s write the equation of the unit circle:

$$x^2 + y^2 = 1.$$

Since $y = 2x$, we can substitute $2x$ for $y$ in the unit circle equation:

$$x^2 + (2x)^2 = 1.$$

This simplifies to:

$$x^2 + 4x^2 = 1$$

$$5x^2 = 1$$

$$x^2 = \frac{1}{5}$$

$$x = \pm \frac{1}{\sqrt{5}}$$

Substituting these values back into $y = 2x$, we get:

$$y = 2(\frac{1}{\sqrt{5}}) = \frac{2}{\sqrt{5}}$$

$$y = 2(-\frac{1}{\sqrt{5}}) = -\frac{2}{\sqrt{5}}$$

Hence, the points of intersection are:

$$ \left( \frac{1}{\sqrt{5}}, \frac{2}{\sqrt{5}} \right)$$ and $$ \left( -\frac{1}{\sqrt{5}}, -\frac{2}{\sqrt{5}} \right).$$

Given the unit circle, find the coordinates of the point where the angle θ intersects the unit circle Let θ = 45 degrees

To find the coordinates of the point where the angle $\theta = 45^\circ$ intersects the unit circle, we use the fact that the unit circle has a radius of 1. The coordinates on the unit circle are given by $(\cos \theta, \sin \theta)$.

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

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

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

Find the cosine values of the angles on the unit circle

Given the angle $\theta = \frac{5\pi}{3}$, we need to find the cosine value.

The unit circle coordinates at an angle $\theta$ are given by $(\cos(\theta), \sin(\theta))$. For $\theta = \frac{5\pi}{3}$, the angle is in the fourth quadrant where the cosine is positive and sine is negative.

Using reference angles, we can see that $\frac{5\pi}{3}$ is equivalent to $-\frac{\pi}{3}$ or $2\pi – \frac{\pi}{3}$. Thus, the cosine value is:

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

From the unit circle, we know that $\cos\left(\frac{\pi}{3}\right) = \frac{1}{2}$. Therefore,

$$\cos\left(\frac{5\pi}{3}\right) = \frac{1}{2}$$