my daughter has a question and I am lost how to solve it.
I have a rectangular box with the following dimensions (see below picture)
Height: $2x-1$
Width: $x+8$
Length: $2x+4$
the line running across the rectangle from bottom left corner to top right corner (sorry don't know name of): $3x+9$
'Setup an equation and solve for $x$' - I don't know how to find $x$ given the above information
I'm pretty sure I could work out the rest of the question once I know what $x$ is
First find the diagonal of the top side (using Pythagoras theorem in the triangle formed by the top side's diagonal, length and width):
$(x + 8) ^ 2 + (2x + 4) ^ 2 = D^2$
Then using pythagoras theorem in the triangle formed by the body diagonal, top side's diagonal and the height we get:
$D^2 + (2x - 1) ^ 2 = (3x + 9) ^ 2$
Comparing the 2 above equations we get:
$(x + 8) ^ 2 + (2x + 4) ^ 2 = (3x + 9) ^ 2 - (2x - 1) ^ 2$
Now solve for $x$.