Question 1115568
A lumber mill cuts rectangular beams from circular logs.
 If diameter of the log is 16 inches and the cross-sectional area of the beam is 120 square inches.
find the dimensions of the cross section of the beam correct to the one decimal place.
:
A rectangular beam from a circular log is a square. 
The diameter of the log is the hypotenuse of the cross section of the square beam
:
let L = one side of the cross section of the beam,
let w = the other side
:
L*w = 120
L = 120/w
: 
using Pythagoras:
L^2 + w^2 = 16^2
L^2 = 256 - w^2
L = {{{sqrt(256-w^2)}}}
plot these two equations
{{{ graph( 300, 200, -3, 18, -3, 18, 120/x, sqrt(256-x^2)) }}}
points of intersection
9.1355287, 13.1355287 and 13.1355287, 9.1355287
correct to one decimal point. cross section 
length = 13.1 inches; width 9.1 inches