An isosceles triangle consists of two legs with equal length, and a base. So, we can call its three sides [tex] b, l, l [/tex], where [tex] b [/tex] stands for base, and [tex] l [/tex] stands for leg.
Since the perimeter [tex] 2p [/tex] is the sum of the three sides, we have
[tex] 2p = b+l+l = b+2l [/tex]
In this case, the lengths of perimeter and base are known, so let's plug those values in the formula:
[tex] 1 = 0.4+2l [/tex]
In order to solve for [tex] l [/tex], let's subtract 0.4 from both sides...
[tex] 0.6 = 2l [/tex]
...and divide both sides by 2:
[tex] 0.3 = l [/tex]
So, the legnth of a leg is 0.3
