### 11.1 Areas of rectangles

```
The area of a square is the square of the length of
a side. (A = s2)
s
s

If two figures are congruent, then they have the
same area.

To a base, is any segment perpendicular to the
line containing the base from any point on the
opposite side.

The area of a rectangle equals the product of its
base and height.

A=bh

The area of a parallelogram equals the product of
a base and the height to that base. (A=bh)
12
5
This green segment
would also be an
altitude. Notice its
length is congruent
to the other
altitudes.
31
12
45°


What this theorem means as the corresponding height is
the length of the altitude that intersects the base you are
using.
In all right triangles it does not matter what the base and
height are, because they are both the legs, (one leg is
always the base and one leg is always the altitude).
However in triangles that are not right triangles the
height must be identified after you decide which
segment you are going to use as your base. A lot of
people struggle with determining the area for these
types of triangles because they simply want to take the
two values you are given as sides and multiply and divide
by 2, where that only works in right triangles. SO BE
CAREFUL
```