Saturday 9 June 2018

GEOMETRIC PROOF OF (a+b)^2


PROOF OF THE FORMULA (a+b) 2 

We all know that  (a+b) 2 = a2+2ab+b2
EVER WONDERED WHY? Lets prove this formula geometrically!

Area of a square with side L is L2  , and we want to find  (a+b) 2 .

Do you find any similarity between these two above?

YES YOU DID! Basically,  (a+b) 2 is the area of a square with side length = (a+b)


We know that the area of this square is (a+b) 2

Now, lets divide this square into following parts: 
Now, our square contains two squares and two rectangles.

So, the area of the square with side (a+b) = area of two squares + area of rectangles
Now, you can observe that the area of the two squares is a2 and b2, and the area of the two rectangles is ab and ab.
So, lets add area of all parts of the square of length (a+b) :
= a2 + ab + ab + b2
= a2 + 2ab + b2
As the Area of square of length (a+b) =  a2 + 2ab + b2
Hence, (a+b)2 = a2+2ab+b2

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