How to find points closest/furthest from the origin for $r = 1 + \cos\theta$?
Find $\frac{dr}{d\theta} = -\sin\theta$. Set $- \sin\theta = 0$, so $\theta = 0, \pi$. Evaluate r at these points: $r(0) = 2$, $r(\pi) = 0$. The closest point is 0, the furthest is 2.
How do you find the equation of the tangent line to $r = \sin(2\theta)$ at $\theta = \frac{\pi}{4}$?
1. Find x and y in terms of θ: $x = r\cos(\theta) = \sin(2\theta)\cos(\theta)$, $y = r\sin(\theta) = \sin(2\theta)\sin(\theta)$. 2. Compute $\frac{dx}{d\theta}$ and $\frac{dy}{d\theta}$. 3. Calculate $\frac{dy}{dx} = \frac{dy/d\theta}{dx/d\theta}$ at $\theta = \frac{\pi}{4}$. 4. Find the (x, y) coordinates at $\theta = \frac{\pi}{4}$. 5. Use the point-slope form to write the equation of the tangent line.
How do you convert the Cartesian equation $x^2 + y^2 = 9$ to polar form?
1. Recall that $r^2 = x^2 + y^2$. 2. Substitute $r^2$ for $x^2 + y^2$ in the given equation. 3. The polar form is $r^2 = 9$, which simplifies to $r = 3$.
How to find the slope of the tangent line to $r = 2\cos(\theta)$ at $\theta = \frac{\pi}{3}$?
How do you find the x-coordinate of a point on the polar curve $r = 4\sin(\theta)$ when $\theta = \frac{\pi}{6}$?
1. Calculate r: $r = 4\sin(\frac{\pi}{6}) = 4 * \frac{1}{2} = 2$. 2. Use the formula $x = r\cos(\theta)$: $x = 2\cos(\frac{\pi}{6}) = 2 * \frac{\sqrt{3}}{2} = \sqrt{3}$.
How do you find the y-coordinate of a point on the polar curve $r = 2 + \cos(\theta)$ when $\theta = \frac{\pi}{2}$?
1. Calculate r: $r = 2 + \cos(\frac{\pi}{2}) = 2 + 0 = 2$. 2. Use the formula $y = r\sin(\theta)$: $y = 2\sin(\frac{\pi}{2}) = 2 * 1 = 2$.
How do you determine the values of $\theta$ where the polar curve $r = 3\sin(\theta)$ intersects the x-axis?
1. The x-axis corresponds to $y = 0$. 2. Set $y = r\sin(\theta) = 0$. 3. This implies $\sin(\theta) = 0$ (since r is not always zero). 4. Solve for $\theta$: $\theta = n\pi$, where n is an integer.
How do you determine the values of $\theta$ where the polar curve $r = 2\cos(\theta)$ intersects the y-axis?
1. The y-axis corresponds to $x = 0$. 2. Set $x = r\cos(\theta) = 0$. 3. This implies $\cos(\theta) = 0$ (since r is not always zero). 4. Solve for $\theta$: $\theta = \frac{\pi}{2} + n\pi$, where n is an integer.
Explain how to convert a polar equation to a Cartesian equation.
Use the relations $x = r\cos\theta$, $y = r\sin\theta$, and $r = \sqrt{x^2 + y^2}$ to eliminate r and θ and express the equation in terms of x and y.
Explain how to find points furthest/closest from the origin for a polar function.
Find $\frac{dr}{d\theta}$, set it equal to zero, solve for $\theta$, and plug the $\theta$ values back into the original equation to find the corresponding r values. Also, check endpoints.
Why is it useful to convert polar equations to Cartesian equations?
It allows for easier visualization and graphing on a traditional x-y coordinate plane, especially for complex functions.
Explain the significance of the first derivative of r with respect to θ.
It represents the radial component of the curve and indicates the instantaneous rate of change of the distance from the origin.
Explain the significance of the second derivative of r with respect to θ.
It represents the radial curvature of the curve and indicates the rate of change of the curvature.
What is the relationship between polar and parametric equations?
Polar equations can be expressed parametrically using $x = r\cos\theta$ and $y = r\sin\theta$, where $\theta$ is the parameter.
What information does $\frac{dy}{dx}$ provide about a polar curve?
It gives the slope of the tangent line to the curve at a given point in Cartesian coordinates, indicating the direction of the curve at that point.
Why is the chain rule important when finding $\frac{dy}{dx}$ for polar functions?
Because y and x are both functions of r and θ, and r is a function of θ, the chain rule is needed to relate the derivatives.
Describe the process of finding the tangent line to a polar curve at a specific angle.
Calculate $\frac{dy}{dx}$ at the given angle, find the x and y coordinates using $x = r\cos\theta$ and $y = r\sin\theta$, then use the point-slope form to find the equation of the tangent line.
Explain how trigonometric identities are used in polar coordinate problems.
Trigonometric identities are used to simplify expressions, convert between polar and Cartesian coordinates, and solve equations involving trigonometric functions of θ.