Unit Circle

Explore the unit circle and its relationship to angles, radians, trigonometric ratios, and coordinates in the coordinate plane.

Evaluate the integral of cos^3(x)sin(x) with respect to x

Evaluate the integral of cos^3(x)sin(x) with respect to x

To evaluate the integral of $ \cos^3(x)\sin(x) $ with respect to $ x $, we use a substitution method:

Let $ u = \cos(x) $, then $ du = -\sin(x) dx $. Consequently:

$$ \int \cos^3(x)\sin(x) dx = \int u^3 (-du) = -\int u^3 du $$

Now integrate:

$$ -\int u^3 du = -\frac{u^4}{4} + C $$

Substitute back $ \cos(x) $ for $ u $:

$$ -\frac{\cos^4(x)}{4} + C $$

The final answer is:

$$ -\frac{\cos^4(x)}{4} + C $$

Determine the cosine of an angle given in radians and convert it to degrees

Determine the cosine of an angle given in radians and convert it to degrees

Given an angle $ \theta = \frac{7\pi}{6} $ radians, we need to determine its cosine and convert the angle to degrees.

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First, convert the angle to degrees:\n

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$$ \theta = \frac{7\pi}{6} \cdot \frac{180^\circ}{\pi} = 210^\circ $$

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The angle $ 210^\circ $ lies in the third quadrant where the cosine is negative.

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Using the unit circle, we know:

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$$ \cos(210^\circ) = \cos(180^\circ + 30^\circ) = -\cos(30^\circ) $$

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Since $ \cos(30^\circ) = \frac{\sqrt{3}}{2} $, we have:

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$$ \cos(210^\circ) = -\frac{\sqrt{3}}{2} $$

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Thus, the cosine of $ \frac{7\pi}{6} $ radians is $ -\frac{\sqrt{3}}{2} $ and the angle in degrees is $ 210^\circ $.

Find the value of sec(θ) for θ in the unit circle

Find the value of sec(θ) for θ in the unit circle

To find the value of $ \sec(\theta) $ for $ \theta $ in the unit circle, we need to recall the definition of secant. The secant function is the reciprocal of the cosine function:

$$ \sec(\theta) = \frac{1}{\cos(\theta)} $$

Given that $ \theta $ is an angle in the unit circle, let’s consider $ \theta = \frac{\pi}{4} $ as an example. For this angle:

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

Thus,

$$ \sec\left(\frac{\pi}{4}\right) = \frac{1}{\frac{\sqrt{2}}{2}} = \sqrt{2} $$

Find the secant line to the unit circle that is equidistant from the x-axis

Find the secant line to the unit circle that is equidistant from the x-axis

To find the secant line to the unit circle that is equidistant from the $x$-axis, we use the equation of the unit circle

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

and the general equation of a line

$$ y = mx + b $$

Since the secant line is equidistant from the $x$-axis, the $y$-intercept $b$ must satisfy the condition that the distances from $b$ to the points of intersection with the circle are equal. So, we solve:

Substitute $y = mx + b$ into the circle

Determine the exact values of sine and cosine for the angle π/4 using the unit circle

Determine the exact values of sine and cosine for the angle π/4 using the unit circle

To find the exact values of sine and cosine for the angle $ \frac{\pi}{4} $, we use the unit circle.

For $ \theta = \frac{\pi}{4} $, the coordinates on the unit circle are:

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

Since $ \frac{\pi}{4} $ is an angle in the first quadrant where sine and cosine values are positive, we use the 45-degree reference angle values. We have:

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

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

Thus, the exact values are:

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

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

Identify the coordinates of specific angles on the unit circle

Identify the coordinates of specific angles on the unit circle

To find the coordinates of specific angles on the unit circle, remember that the unit circle has a radius of 1.

For the angle $\theta = \frac{\pi}{4}$, the coordinates are:

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

Find the area of a sector in a unit circle with a central angle of θ radians

Find the area of a sector in a unit circle with a central angle of θ radians

The formula to find the area of a sector in a unit circle is:

$$ A = \frac{1}{2} \theta $$

where $ \theta $ is the central angle in radians.

For example, if $ \theta = \frac{\pi}{4} $:

$$ A = \frac{1}{2} \times \frac{\pi}{4} = \frac{\pi}{8} $$

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