A uniform border on a framed photograph has the same area as the photograph. What are the outside dimensions of the border if the dimensions of the photograph are 25cm by 20cm?
What would a diagram for this question look?
Hi sinjid9,
the attachment shows a diagram.
You can either subtract the photo area from the area inside the outer
perimeter of the frame
$\displaystyle (20+2x)(25+2x)-500=500$
or add up the areas inside the border
$\displaystyle 2(25+2x)x+2(20)x=500$
Hence, you must solve
$\displaystyle 2x^2+45x-250=0$
As this doesn't factorise easily, use
$\displaystyle x=\frac{-45\pm\sqrt{45^2-4(2)(-250)}}{2(2)}$
to find x.
You should get a value slightly greater than 4