1 There is only one straight line between two points. The shortest line segment between two points is 3. The same angle or the complementary angle of the same angle is equal. 4. The same angle or the complementary angle of the same angle is equal. 5. Only one straight line is perpendicular to the known straight line. 6. Among all the line segments connected with points on a straight line, the shortest parallel axiom of a vertical line segment passes through a point outside the straight line. There is only one straight line parallel to this straight line. If both lines are parallel to the third line, the two lines are parallel to each other. The isosceles angles are equal and the two straight lines are parallel to each other. 10, the offset angles are equal, and the two straight lines are parallel to each other. 1 1 is complementary to the inner corner of the side, and the two straight lines are parallel to each other. 13, two straight lines are parallel. The internal dislocation angle is equal to 14, and the two straight lines are parallel. Theorem The sum of two sides of a triangle is greater than the third side 15. The difference between two sides of the reasoning triangle is less than the third side 17. The sum of the interior angles of a triangle is theorem. The sum of the three interior angles of a triangle is equal to 180 18. The two acute angles of a right triangle complement each other 19. The outer corner of a triangle. It is deduced from the sum of two non-adjacent internal angles that one external angle of a triangle is larger than the corresponding side of any non-adjacent internal angle, that is, 2 1 congruent triangles, and the corresponding angle is equal to 22. The edge axiom (SAS) has two triangles with equal angles. The edge axiom (ASA) has two triangles with equal angles. The edge axiom (AAS) has two triangles with equal angles. The congruent 25 side axiom (SSS) of two triangles corresponding to the opposite sides of two angles and one angle and the congruent 26 hypotenuse and right angle axiom (HL) of two triangles corresponding to three sides. Two right-angled triangles with a hypotenuse and a right-angled side are congruent. Theorem 1 A point on the bisector of an angle is equal to the distance between two sides of the angle. Theorem 2 To a point with equal distance on both sides of an angle, on the bisector of this angle, the bisector of 29 angles is the set of all points with equal distance on both sides of this angle. The nature theorem of isosceles triangle 30 The two base angles of an isosceles triangle are equal (that is, equilateral and equilateral). 3 1 Inference 1 The bisector of the top angle of the isosceles triangle bisects the bottom and is perpendicular to the bisector of the top angle of the isosceles triangle with the bottom 32. The midline on the bottom edge coincides with the height on the bottom edge. Inference 3 All angles of an equilateral triangle are equal, and each angle is equal to 60 34 isosceles triangle. If a triangle has two equal angles, then the opposite sides of the two angles are also equal (equilateral) 35 Inference 1 A triangle with three equal angles is an equilateral triangle 36 Inference 2 An isosceles triangle with an angle equal to 60 is an equilateral triangle 37 in a right triangle. If an acute angle is equal to 30, then the right-angled side it faces is equal to half of the hypotenuse. The median line of the hypotenuse of a right triangle is equal to half of the hypotenuse. Theorem 39 A point on the vertical line of a line segment is equal to the distance between the two endpoints of this line segment. The inverse theorem and the point where the two endpoints of a line segment are equal. On the midline of this line segment, the midline of line segment 4 1 can be regarded as a set of all points with equal distance from both ends of the line segment. Theorem 42: Two graphs that are symmetrical about a straight line are congruent. Theorem 43: Two figures are symmetrical about a straight line, then the symmetry axis is the median vertical line 44 Theorem 3: Two figures are symmetrical about a straight line. If their corresponding line segments or extension lines intersect, then the intersection point is on the axis of symmetry. 45 Inverse Theorem If the straight line connecting the corresponding points of two graphs is bisected vertically by the same straight line, then the two graphs are symmetrical about this straight line. 46 Pythagorean Theorem The sum of squares of two right-angled sides A and B of a right-angled triangle is equal to the square of the hypotenuse C, that is, the inverse theorem of A 2+B 2 = C 2. 47 Pythagorean Theorem If three sides of a triangle have a relationship A 2+B 2 = C 2, then this triangle is a right-angled triangle. Theorem 48 The sum of internal angles of quadrilateral is equal to 360 49, and the sum of internal angles of polygon is equal to 360 50. Theorem The sum of internal angles of n- polygon is equal to (n-2) × 180 5 1. It is inferred that the sum of the external angles of any polygon is equal to 360 52. The property theorem of parallelogram 1 The diagonal of parallelogram is equal to 53. Quality Theorem 2 Parallelogram's opposite sides are equal 54 Inference that parallel lines sandwiched between two parallel lines are equal 55 Parallelogram Property Theorem 3 Parallelogram's diagonal is bisected 56 Parallelogram Judgment Theorem 1 Two sets of parallelograms with equal diagonal are parallelograms 57 Parallelograms Judgment Theorem 2 Two sets of parallelograms with equal opposite sides are parallelograms 58 Parallelograms Judgment Theorem 3 Diagrams are reciprocal. The bisected quadrilateral is a parallelogram 59. Parallelogram Decision Theorem 4. A set of parallelograms with equal opposite sides is parallelogram 60. Rectangular property theorem 1. All four corners of a rectangle are right angles 6 1. Theorem of rectangle properties II. The diagonal lines of the rectangle are equal to 62. Rectangular decision theorem 1. A quadrilateral with three right angles is a rectangle 63. Rectangular decision theorem ii. A parallelogram with equal diagonals is a rectangle. 64 rhombic property theorem 1 All four sides of the rhombus are equal. 65 Diamond Property Theorem 2 Diagonal lines of diamonds are perpendicular to each other, and each diagonal line bisects a set of diagonal lines. 66 diamond area = half of diagonal product. That is, S=(a×b)÷2 67 rhombus decision theorem 1 quadrilateral with four equal sides is rhombus 68 rhombus decision theorem 2 parallelograms with mutually perpendicular diagonals are rhombus 69 square property theorem 1 square property theorem that all four corners are right angles and all four sides are equal to 70 square property theorem 2 two diagonal lines of a square are equal and bisected vertically, and each diagonal line bisects a set of diagonal lines 7/kloc-0.