The quadratic equation of one variable can be transformed into the general form ax? +bx+c=0(a≠0). Cartesian coordinate system and point position, special trigonometric function value, basic properties of circle, positional relationship between straight line and circle, etc.

2. A quadratic equation

An integral equation that contains only one unknown (unary) and the highest order of the unknown is 2 (quadratic) is called unary quadratic equation.

. The quadratic equation of one variable can be transformed into the general form ax? +bx+c=0(a≠0), where ax It is called quadratic term and a is the coefficient of quadratic term; Bx is called a linear term, and b is the coefficient of the linear term; C is called a constant term.

3. Special trigonometric functions

Special trigonometric function values generally refer to trigonometric function values of angles of 30, 45 and 60. Trigonometric function values of these angles are often used. And using the formulas of trigonometric functions of the sum and difference of two angles, we can get some trigonometric function values of other angles. cos30 = 1，tan45 = 1 .

4, the basic properties of the circle

A semicircle or diameter subtends a right angle.

Any triangle must have a circumscribed circle.

In the same plane, the distance to a fixed point is equal to the trajectory of a fixed-length point, which is a circle with the fixed point as the center and the fixed length as the radius.

In the same circle or in the same circle, the arcs with equal central angles are equal.

The angle of a circle opposite to the same arc is equal to half the central angle of the circle.

The same circle or the same circle has the same radius.

You can make a circle after three o'clock.

Two equal-length arcs are equal-length arcs.

In the same circle or in the same circle, the arcs with equal central angles are equal.

The diameter of a chord bisected by the center of the circle is perpendicular to the chord.