Question 314374
Use the Pythagorean theorem,
{{{L1^2+L2^2=HYP^2}}}
{{{60^2+L2^2=(L2+20)^2}}}
{{{L2^2+3600=L2^2+40L2+400}}}
{{{40L2=3200}}}
{{{highlight(L2=80)}}}
{{{HYP=L2+20=100}}}
THe longer leg is 80m long.