In triangle △JKL, ∠JKL is right angle, and KM is an altitude. JL=25 and JM=5, find KM.
By similar triangles: JM : MK = MK : ML
JL = 25 and JM = 5 ---> ML = 20
Substituting: 5 : MK = MK : 20 ---> MK2 = 5·20 ---> MK2 = 100 ---> MK = 10
