Cardioid and limacon of Pascal
[19/74%]Find the radius of curvature of the curve given by the following polar equation: the cardioid .
From a point on a circle of diameter , secants are drawn. On each of them, on both sides of the other point of intersection with the circle, segments of length are laid off. Find the locus of their endpoints. (Limaçon of Pascal.)
For the epicycloid becomes a curve called the cardioid. Show that the equation of the cardioid, in suitably chosen polar coordinates, has the form .
Show that the cardioid (see the preceding problem) is a special case of the limaçon of Pascal (see problem 141).
Find the angle between the tangent and the polar radius of the point of tangency for the following curves:
the spiral of Archimedes ;
the hyperbolic spiral ;
the logarithmic spiral ;
the cardioid ;
the arc of the lemniscate of Bernoulli .
Prove that the evolute of a cardioid is also a cardioid.
Find the area of the figure bounded by the curve:
(ellipse);
(evolute of the ellipse);
(limaçon);
(epicycloid);
(hypocycloid);
(cardioid).
Find the area of the figure bounded by curves given in polar coordinates.
;
;
(cardioid);
(limaçon);
(find the area of one petal);
;
;
(ellipse);
(hyperbola);
;
;
.
Find the area of the figure bounded by:
the outer loop of the limaçon ;
its inner loop.
Inside a circle of radius there is a point at distance from the center. A curve is formed by the feet of the perpendiculars dropped from the point onto the tangents to the circle. Find the area of the figure bounded by this curve.
Find the length of the arc of the curve:
(logarithmic spiral);
(cardioid);
;
;
.
Find the volume of the solid formed by rotating Pascal's limaçon around the polar axis:
(outer loop);
(inner loop);
.
Find the volume of the solid formed by rotating the cardioid around the line .
(Limaçon of Pascal.) On a circle, two diametrically opposite points and are taken, with . A ray rotates about the point . Let be the variable point of intersection of the line containing this ray with the circle. On the line , from the point in the direction of the ray, a segment of length is laid off. Write, in generalized polar and rectangular coordinates, the equation of the curve traced by the point as the ray rotates, taking the point as the origin and the direction as the positive direction of the axis .
Indicate the angle at which the limaçon of Pascal from the preceding problem intersects the axis at the origin
for ;
for ?
Prove that the locus of the feet of the perpendiculars dropped from a given point onto the tangents to a given circle is a limaçon of Pascal.
(Cardioid.) A circle of radius is given, and on it two diametrically opposite points and . A ray rotates about the point . Let the line containing this ray intersect the circle at a variable point . On this line, from the point in the direction of the ray, a segment equal to the diameter of the circle is laid off. Write, in generalized polar and rectangular coordinates, the equation of the curve traced by the point as the ray rotates, taking the point as the origin, and the ray as the positive direction of the axis .
Prove that the following curves are cardioids:
the locus of points symmetric to a point , lying on a given circle, with respect to all possible tangents to this circle;
the locus of the feet of the perpendiculars dropped from a point , lying on a given circle, onto all possible tangents to this circle.
A circle is given, and on it a point . Prove that the circles passing through the point , whose centers lie on the given circle, sweep out a region bounded by a certain cardioid.