http://www.ck12.org Chapter 10. Perimeter and Area
Know What?The Brazilian flag is to the right. The flag has dimensions of 20×14 (units vary depending on the
size, so we will not use any here). The vertices of the yellow rhombus in the middle are 1.7 units from the midpoint
of each side.
Find the total area of the flag and the area of the rhombus (including the circle).Do not round your answers.
Area of a Trapezoid
Recall that a trapezoid is a quadrilateral with one pair of parallel sides. The lengths of the parallel sides are the bases.
The perpendicular distance between the parallel sides is the height, or altitude, of the trapezoid.
To find the area of the trapezoid, let’s turn it into a parallelogram. To do this, make a copy of the trapezoid and then
rotate the copy 180◦.
Now, this is a parallelogram with heighthand baseb 1 +b 2. Let’s find the area of this shape.
A=h(b 1 +b 2 )Because the area of this parallelogram is made up of two congruent trapezoids, the area of one trapezoid would be
A=^12 h(b 1 +b 2 ).