Welcome to our lesson on polygon areas! A polygon is a closed shape made of straight lines. We can see different types of polygons here: triangles with 3 sides, squares with 4 equal sides, pentagons with 5 sides, and hexagons with 6 sides. Today we'll learn how to calculate the area of these shapes.
Let's start with rectangles! A rectangle has four sides with opposite sides equal. To find the area of a rectangle, we multiply length times width. In this example, our rectangle is 6 units long and 4 units wide. So the area equals 6 times 4, which is 24 square units. We can see this by counting the unit squares inside.
Now let's learn about triangles! A triangle has 3 sides and 3 corners. To find the area of a triangle, we use the formula: Area equals one-half times base times height. The height must be perpendicular to the base, forming a right angle. In this example, our triangle has a base of 9 units and a height of 6 units. So the area equals one-half times 9 times 6, which is 27 square units.
A parallelogram has opposite sides that are parallel and equal. To find the area of a parallelogram, we multiply base times height. The height is the perpendicular distance between the parallel sides. In this example, our parallelogram has a base of 8 units and a height of 5 units. So the area equals 8 times 5, which is 40 square units. Notice that we can transform a parallelogram into a rectangle with the same area!