How could I show why the formula for the area of a parallelogram is A= b*h?
Knowing the formula for the area of a rectangle, how could I show why the formula for the area of a parallelogram is A= b*h?
by the way I am 13 so try not to use complicated language! thanx 
Cut a triangle off of the parallelogram… so that the parallelogram becomes a right trapezoid and the triangle is also a right angled triangle. Add that triangle back onto the right trapezoid on the other side, so that they become a rectangle.
This is a simple geometric illustration. Area is perfectly preserved. b stays b, the base of the rectangle is the base of the parallelogram. But h goes from being the height of the parallelogram to being the width of the rectangle.
Cut a triangle off of the parallelogram… so that the parallelogram becomes a right trapezoid and the triangle is also a right angled triangle. Add that triangle back onto the right trapezoid on the other side, so that they become a rectangle.
This is a simple geometric illustration. Area is perfectly preserved. b stays b, the base of the rectangle is the base of the parallelogram. But h goes from being the height of the parallelogram to being the width of the rectangle.
References :
drop perpendiculars down from the two top vertices to describe two triangles, one inside one outside the original shape, use geometric axioms about opposite sides of the paralleogram forming equal hypotenuses and the vertical sides of the triangles being equal proving that the two triangles are congruent, then transpose the internal triangle to cover the external triangle and so form a rectangle with the same base and perpendicular height of the original shape
References :