Question 917394

height is {{{12ft}}}, 
base is {{{8ft + 1ft = 9ft}}} ....you have right angle triangle where 

hypotenuse is the {{{ladder}}}

 {{{ladder^2 = (12ft)^2 + (9ft)^2}}}

{{{ladder = sqrt(144ft^2+81ft^2)}}}

{{{ladder = sqrt(225ft^2)}}}

{{{ladder = 15ft}}}