Compulsory 2: Straight lines and circles are almost not learned, do they have a great impact on the

"Returning to the Hometown Doll Book" expresses his deep feelings that life is easy to grow old, the vicissitudes of the world, things are wrong, and he is at a loss. also wrote out the feelings of long-term customers. It is a long-time guest in a foreign land, remembering the hometown of the sentimental poem.

Original text: Two poems of the homecoming puppet book.

Tang Dynasty: He Zhizhang.

When he left home and returned to his eldest child, his hometown accent has not changed, and his sideburns have declined.

When the children don't know each other, they smile and ask where the guests are from.

I left my hometown when I was young and didn't return until the twilight of my life. My native accent hasn't changed, but the hair on my sideburns has fallen out. The children saw me, and none of them knew me. They smiled and asked: Is this guest from **?

There must be an impact, many times you calculate and find that you can't pass this point, so let's lay a good foundation in front of you first, and continue to work hard.

The impact is great, you first think about why you talk about straight lines and circle calculations first, sometimes he is to pave the way for the next class, or you need to understand this knowledge point.

This impact is still relatively large, but don't worry too much, in the conic curve, the relationship between the straight line and the conic curve is a little more examined, and you can master the equation of the straight line.

Conic curvesThe second definition is that the trajectory of a point where the ratio of the distance to the fixed point to the distance to the fixed line e is constant is called a conic curve. When 0 parabola.

When e>1 is hyperbola.

Conic curves include ellipses (a special case of a circle being an ellipse), parabola, and hyperbola.

Conic curve features:

1. From the form of the equation:

Make a Cartesian coordinate system.

, the equations of these curves (including circles) f(x,y)=0 are all binary quadratic equations, so they are collectively referred to as quadratic curves.

2. From the point of view of the set (or trajectory) of points:

They are all ratios of the distances from the fixed point and the fixed line in the flat vertical orange plane, and both are the set (or trajectories) of constant points, except that they are elliptical when they are 0<<1, parabola when they are =1, and hyperbola when they are 1.

3. From the shape generation process of the curve, we can see the potato ball

The conic curve can be regarded as the perimeter of the cross-section obtained by the conic surface of different planes, so the ellipse (including the circle), the parabola, and the hyperbola are collectively referred to as the conic curve.

The second definition of the conical bën line is: the distance to the fixed point.

The ratio e of the distance to the definite line dao is the orbit of a constant point.

The engraving is called a conic curve. When 01 is hyperbola.

Conic curves include ellipses (a special case of a circle being an ellipse), parabola, and hyperbola. (incomplete) uniform definition of conic curves (quadratic curves):

The quotient of the distance to the fixed point (focus) and the distance to the fixed line (alignment) is the trajectory of the point with the constant e (eccentricity).

Ellipse: The ratio of the distance from a moving point to a fixed point in a fixed point in a plane is a normal number e less than 1. The set of distances from one moving point to two fixed points (focal points) in the plane and points equal to fixed length 2a (let the moving point be p and the two fixed points are f1 and f2, then pf1 + pf2 = 2a).

The fixed point is the focal point of the ellipse, the fixed line is the alignment of the ellipse, and the constant e is the eccentricity of the ellipse.

Hyperbola: The ratio of the distance from a moving point to a fixed point to a fixed line in the plane is a constant e greater than 1; The difference in distance between one moving point and two fixed points (focal points) in the plane is equal to the set of points of fixed length 2a (let the moving point be p, and the two fixed points are f1 and f2, then pf1-pf2 = 2a) the fixed point is the focal point of the hyperbola, the fixed line is the alignment of the hyperbola, and the constant e is the eccentricity of the hyperbola.

Parabola: The ratio of the distance from a moving point to a fixed point in a plane to a fixed line is equal to 1. The fixed point is the focal point of the parabola, and the fixed line is the alignment of the parabola.