The seventh grade mathematical mind map: intersection line and parallel line; The seventh grade mathematical mind map: the relationship between variables; Seventh grade mathematical mind map: seventh grade mathematical mind map with life symmetry; The seventh grade mathematics mathematics triangle knowledge point induction: the preliminary probability 1, the sum of any two sides of the triangle is greater than the third side, and the difference between any two sides is less than the third side.
2. The sum of the three internal angles of a triangle is equal to 180 degrees.
3. The two acute angles of a right triangle are complementary.
4. The three bisectors of a triangle intersect at one point, and the three median lines intersect at one point; The straight lines of three heights of a triangle intersect at one point.
5. Conditions for congruence of right triangle:
The hypotenuse and a right-angled side correspond to the congruence of two right-angled triangles, abbreviated as? Hypotenuse, right angle? Or? HL？ .
As long as any two sides are equal, the two right triangles are congruent.
6. Conditions of triangle congruence:
(1) Three sides correspond to the congruence of two triangles, abbreviated as? Side by side? Or? SSS？ .
(2) Two triangles have two angles and their sides are congruent, abbreviated as? Corner? Or? Asa? .
(3) Two angles and the opposite side of an angle correspond to the congruence of two triangles, abbreviated as? Corner? Or? AAS？ .
(4) Two triangles with equal included angles are congruent, abbreviated as? Corner? Or? SAS？ .
7, the characteristics of isosceles triangle:
(1) A triangle with two equal sides is called an isosceles triangle;
(2) The isosceles triangle is an axisymmetric figure;
(3) The bisector of the top angle of the isosceles triangle, the median line on the bottom edge, and the coincidence on the bottom edge (also known as? Three lines in one? ), their straight lines are the symmetry axes of isosceles triangles.
(4) The two base angles of an isosceles triangle are equal.