Question 906605
let's hypotenuse be {{{c}}}
let's legs be {{{a}}} and {{{b}}}

given:

{{{c=14ft}}}

since you have 45-45-90 triangle means legs are same length: {{{a=b}}} 

by Pythagorean theorem {{{c^2=a^2+b^2}}}

since {{{a=b}}} and {{{c=14 feet}}}, we have 

{{{14^2=b^2+b^2}}}

{{{14^2=2b^2}}}

{{{14*14/2=b^2}}}

{{{14*7=b^2}}}

{{{98=b^2}}}

{{{sqrt(98)=b}}}
{{{sqrt(49*2)=b}}}


{{{7sqrt(2)ft=b}}} and {{{7sqrt(2)ft=a}}}.........the length of a leg of the triangle

Part b:

the perimeter of the triangle is {{{P=a+b+c}}}

{{{P=7sqrt(2)ft+7sqrt(2)ft+14ft}}}

{{{P=14sqrt(2)ft+14ft}}}

{{{P=14(sqrt(2)+1)ft}}}