Question 186855
{{{(sqrt(5) - 3)*(sqrt(5) -1)}}}
{{{sqrt(5)*sqrt(5) - 1*sqrt(5) - 3*sqrt(5) + 3}}}
{{{5 - 4*sqrt(5) + 3}}}
{{{8 - 4*sqrt(5)}}}

Also How far above the water would a submarine periscope have to be to locate a ship 3.5 mi away? The equation for the distance in miles that the lookout can see is D=1.4/h, where h is the height in feet above the surface of the water. 
{{{D=1.4/h}}}
{{{3.5 = 1.4/h}}}
{{{h = 1.4/3.5}}}
{{{h = 0.4}}} feet above the water