The first chapter \x09 quadratic radical

1 quadratic root: the formula in the form of () is a quadratic root;

Attribute: () is non-negative;

.

2 Multiplication and division of quadratic root:;

.

Quadratic root addition and subtraction: when adding and subtracting quadratic roots, first merge the simplest quadratic roots of Huawei, and then merge the quadratic roots with the same number of roots.

4 Helen-Qin Jiushao formula: s is the area of triangle and p is.

Chapter II Quadratic Equation in One Variable

1 unary quadratic equation: an equation with algebraic expressions on both sides of the equal sign and only one unknown number, the highest order of which is 2.

2 the solution of quadratic equation in one variable

Matching method: match one side of the equation into a completely flat way, and then square both sides;

Formula method:

Factorization: the product of two factors on the left and zero on the right.

3 The application of quadratic equation in one variable in practical problems

Vieta Theorem: Let it be the two roots of the equation, then there is.

Chapter III Rotation

1 Rotation of the graph

Rotation: A graphic transformation in which a graphic rotates by an angle around a certain point.

Property: the distance from the corresponding point to the rotation center is equal;

The included angle between the corresponding point and the line segment connecting the rotation center is equal to the rotation angle.

Graphic consistency before and after rotation.

2. Center symmetry: if one graph rotates around a point by 180 degrees and coincides with another graph, then the two graphs are symmetrical about the center of this point;

Centrally symmetric figure: a figure rotates 180 degrees around a certain point and can coincide with the original figure, so it is called centrosymmetric;

Three coordinates of a point with symmetrical origin.

The fourth chapter circle

1 Definition of circle, center, radius, diameter, arc, chord and semicircle

2 Diameter perpendicular to the chord

A circle is an axisymmetric figure, and any straight line with a diameter is its axis of symmetry;

The diameter perpendicular to the chord divides the chord in two and squares the two arcs opposite to the chord;

The diameter of the chord is perpendicular to the chord, and the two arcs opposite the chord are equally divided.

3 Arc, chord and central angle

In the same circle or in the same circle, equal central angles have equal arcs and equal chords.

4 circle angle

In the same circle or equal circle, the circumferential angle of the same arc or equal arc is equal, which is equal to half the central angle of the arc;

The semicircle (or diameter) faces the right angle, and the 90-degree angle faces the diameter.

The positional relationship between five points and a circle

The point is not in the circle.

Points on the circle d=r

Point dR+r in the circle

Circumscribed =R+r

Intersecting R-r