S area a bottom h height area = bottom height 2s=ah2 triangle height = area 2 bottom.

Elementary school students' mathematical triangle formula daquan: triangle base = area 2 height

1. Definition of triangle: A figure surrounded by three line segments (the endpoints of every two adjacent line segments are connected or overlapped) is called a triangle.

Draw a vertical line from the vertex of the triangle to its opposite side. The line segment between the vertex and the vertical foot is called the height of the triangle, and this pair of sides is called the bottom of the triangle. This triangle is only three stories high. Key point: the drawing method of triangle height.

3. Angle characteristics: physical characteristics: stability. Such as: tripod for bicycles, tripod on telephone poles.

4. Characteristics of sides: the sum of any two sides is greater than the third side.

5. For the convenience of expression, letters A, B and C are used to represent the three vertices of a triangle, which can be represented as triangle ABC.

6. Classification of triangles: according to the size of angles: acute triangle, right triangle and obtuse triangle. Divided by side length: triangle with unequal sides and isosceles triangle (equilateral triangle or regular triangle is a special isosceles triangle). The three sides of an equilateral triangle are equal and each angle is 60 degrees. (The concepts of top angle, bottom angle, waist and bottom)

7. A triangle with three acute angles is called an acute triangle.

8. A triangle with a right angle is called a right triangle.

9. A triangle with an obtuse angle is called an obtuse triangle.

10, each triangle has at least two acute angles; Each triangle has at most 1 right angles; Each triangle has at most 1 obtuse angles.

A triangle with 1 1 equal sides is called an isosceles triangle.

12. A triangle with three equilateral sides is called an equilateral triangle, also called a regular triangle.

13, an equilateral triangle is a special isosceles triangle.

14, and the sum of the internal angles of the triangle is equal to 180 degrees. The sum of the internal angles of the quadrilateral is 360, and the calculation and format of the correlation degree.

15, combination of figures: two identical triangles can definitely be combined into a parallelogram.

16. Two identical triangles can be used to form a parallelogram.

17. Two identical right triangles can be combined into a parallelogram, a rectangle and a big triangle.

18. Two identical isosceles right triangles can be combined into a parallelogram and a square. Large isosceles right triangle.

19, Dense Shop: The figures that can be Dense Shop are rectangle, square, triangle and regular hexagon.