All Flashcards
What is the formula for average rate of change of (r) with respect to (\theta)?
How do you convert from polar coordinates ((r, \theta)) to Cartesian coordinates ((x, y))?
x = r \cos(\theta), y = r \sin(\theta)
How do you convert from Cartesian coordinates ((x, y)) to polar coordinates ((r, \theta))?
r = \sqrt{x^2 + y^2}, \theta = \arctan(\frac{y}{x})
What is the formula for the derivative of a polar function (r = f(\theta))?
How do you find the slope of a tangent line to a polar curve?
What is the formula to find the area enclosed by a polar curve (r = f(\theta)) from (\theta = a) to (\theta = b)?
How to calculate the arc length of a polar curve (r = f(\theta)) from (\theta = a) to (\theta = b)?
What is the general form of a polar equation for a circle centered at the origin?
r = a, where 'a' is the radius of the circle.
What is the polar equation for a line passing through the origin?
, where (c) is a constant angle.
What is the formula for finding points of intersection between two polar curves (r_1(\theta)) and (r_2(\theta))?
Solve the equation (r_1(\theta) = r_2(\theta)) for (\theta). Also, check if the pole (origin) is a point on either curve.
What does a polar graph look like when (r) is constant?
It forms a circle centered at the origin with radius (r).
If the polar graph of (r = f(\theta)) is symmetric about the x-axis, what does this imply about the function?
It implies that (f(\theta) = f(-\theta)), meaning the function is even.
How can you identify relative maxima and minima on a polar graph?
Look for points where the curve reaches its farthest or closest distance from the origin locally.
What does a cardioid polar graph look like?
It has a heart-like shape, typically represented by equations of the form (r = a(1 \pm \cos(\theta))) or (r = a(1 \pm \sin(\theta))).
What does a lemniscate polar graph look like?
It has a figure-eight shape, represented by equations of the form (r^2 = a^2 \cos(2\theta)) or (r^2 = a^2 \sin(2\theta)).
How does the period of a trigonometric function in polar coordinates affect the graph?
The period determines how often the graph repeats itself as (\theta) increases. For example, (r = \sin(2\theta)) completes a full graph in (\pi) radians.
What does it mean if a polar curve passes through the origin?
It means that there exists some value of (\theta) for which (r = 0).
How can you tell if a polar graph is symmetric about the y-axis?
The graph is symmetric about the y-axis if replacing (\theta) with (-\theta) changes the sign of (r), or if replacing (\theta) with (\pi - \theta) leaves the equation unchanged.
What does the slope of the tangent line at a point on a polar graph represent?
It represents the instantaneous rate of change of (y) with respect to (x) at that point, indicating the direction of the curve.
How does the constant term in a polar equation like (r = a + b\cos(\theta)) affect the graph?
The constant term (a) affects the size and position of the graph. If (a = b), it forms a cardioid. If (a < b), it forms a looped curve.
Define polar coordinates.
A coordinate system where a point is located by its distance (r) from the origin and an angle (\theta) from the polar axis.
What is a polar function?
A function defined in polar coordinates, typically in the form (r = f(\theta)), where (r) is the distance from the origin and (\theta) is the angle.
Define relative maximum in polar functions.
A point where the distance (r) from the origin is locally the greatest, changing from increasing to decreasing as (\theta) increases.
Define relative minimum in polar functions.
A point where the distance (r) from the origin is locally the smallest, changing from decreasing to increasing as (\theta) increases.
What is the polar axis?
The reference line ((\theta = 0)) from which the angle (\theta) is measured in polar coordinates, analogous to the positive x-axis in Cartesian coordinates.
Define average rate of change in polar functions.
The change in (r) with respect to (\theta) over an interval, calculated as (\frac{\Delta r}{\Delta \theta} = \frac{r(\theta_2) - r(\theta_1)}{\theta_2 - \theta_1}).
What does it mean for a polar function to be 'expanding'?
The distance (r) from the origin is increasing as (\theta) increases.
What does it mean for a polar function to be 'contracting'?
The distance (r) from the origin is decreasing as (\theta) increases.
Define critical points in polar functions.
Values of (\theta) where the derivative of (r) with respect to (\theta) (i.e., (r'(\theta))) is either zero or undefined. These points are candidates for relative extrema.
What is the significance of (r = 0) in polar coordinates?
It indicates that the point is at the origin, regardless of the value of (\theta).