Question 884718
The diagonal splits the square into two right triangles.
For those right triangles, the diagonal is the hypotenuse,
and sides of the square are the legs.
So, {{{diagonal^2=(4cm)^2+(4cm)^2}}}
{{{diagonal^2=16cm^2+16cm^2}}}
{{{diagonal^2=32cm^2}}}
{{{diagonal=sqrt(32cm^2)}}}
{{{diagonal=sqrt(32)}}}{{{cm}}}
{{{diagonal=sqrt(16*2)}}}{{{cm}}}
{{{diagonal=sqrt(16)*sqrt(2)}}}{{{cm}}}
{{{diagonal=4sqrt(2)}}}{{{cm}}}