Explanation:
Computing
the area of a triangle
The
area of a triangle can be demonstrated as half of the area of a parallelogram which has the same base length and
height.
Calculating the area of a triangle is an elementary problem
encountered often in many different situations. The best known and simplest
formula is:
where b is the length of the base of the
triangle, and h is the height or altitude of the
triangle. (Our
solved example in mathguru.com uses this concept)
The term 'base' denotes any side and 'height' denotes the length
of a perpendicular from the vertex opposite the side onto the line containing
the side itself.
http://en.wikipedia.org/wiki/Triangle#Computing_the_area_of_a_triangle
Area
formulas
The
area of the parallelogram is the area of the blue region, which is the interior
of the parallelogram
§ The
area of the parallelogram to the right (the blue area) is the total area of the
rectangle less the area of the two orange triangles.
The area of the rectangle is
and the area of a single orange triangle is
Therefore, the area of the parallelogram is
(Our solved example in mathguru.com uses this concept)
http://en.wikipedia.org/wiki/Parallelogram
The
above explanation is copied from Wikipedia, the free encyclopedia and is
remixed as allowed under the Creative Commons Attribution- ShareAlike 3.0 Unported
License.
(Our solved example in mathguru.com also uses the below concept.
This is our own explanation, it is not taken from Wikipedia.)
If a Triangle and Parallelogram are on the same base and between
the same parallel lines, then area of triangle is equal to half the area of
parallelogram.