EF07MA31) Establish expressions for calculating the area of triangles and quadrilaterals.
(EF07MA32) Solve and elaborate problems of calculating the area measure of flat figures that can be decomposed by squares, rectangles and/or triangles, using the equivalence between areas.
Before presenting the calculations and polygons, it may be necessary to reinforce the concept of area and its units of measurement, with multiples and submultiples.
When starting to study polygons, it is important to start with the rectangle, due to its simplicity. The teacher should use the blackboard or other available resources, where he will expose the basic elements to obtain the area: base and height.
Next, the formula for obtaining the area must be accompanied by examples and their calculations. The step-by-step detailing is important, as teenagers may have difficulties at this stage.
Afterwards, the process is repeated for the triangle, paying attention to the height. It is important to use examples to obtain the height in different types of triangles: equilateral, isosceles and scalene.
It is important to point out that in this step, procedures for obtaining the area of triangles, such as: trigonometric methods, Heron's formula or for specific cases, will not be inserted.
Practical activity
Using a tape measure, students can calculate the areas of rectangular regions, such as the classroom, desks, and courts.
It is important that the teacher apply exercises for fixing and applying the content. You can get exercises from:
Plane Figures Area: Solved and Commented Exercises
ASTH, Rafael. Lesson plan: triangles and rectangles area (7th grade).All Matter, [n.d.]. Available in: https://www.todamateria.com.br/plano-de-aula-de-matematica-area-de-triangulos-e-retangulos-7-ano/. Access at:
