In a 30-60-90 degree triangle the side lengths are in the proportion x:2x:x*sqrt(3) where x is opposite the 30 degree angle, 2x is opposite the 90 degree angle and x*sqrt(3) is opposite the 60 degree angle.
If 26m is opposite the 90 degree angle then 2x = 26 thus x =13. The short leg is 13 and the long leg is 13*sqrt(3).