Rectangles
The dimensions of a rectangle are referred to as the lengthand width. The
formula for the area of a rectangle is length times width.
Area of a Rectangle = (length) ×(width), or A= lwTriangles
The following rectangle has been divided into two equal triangles by a diag-
onal. Since the area of the rectangle is length times width, you can proba-
bly guess that the area of one of the triangles would be half of length times
width. With triangles, the names “length” and “width” are not commonly
used: side BCis referred to as the baseand side DCis the height. The for-
mula for the area of a triangle is therefore half of the base times height. A
very important thing to remember is that the height must always be at a 90°
angle to the base. Sometimes it is necessary to use the Pythagorean theo-
rem to solve for the height, before the area can be calculated.
Area of a Triangle= ^12 ××(base)××(height) or A= (^12 )bhAHeightBaseCDBwidthlength501 Geometry Questions