In an isosceles triangle, the lateral side is 15 cm, the height drawn to the base is 12 cm.Find: a) the base

In an isosceles triangle, the lateral side is 15 cm, the height drawn to the base is 12 cm.Find: a) the base b) the cosine of the angle at the base c) the median drawn to the lateral side

Consider three AВС:
AB = BC = 15 cm
ВH – height = 12 cm
tr. AВН = НВС
According to Comrade Pythagoras:
HC = 15 ^ 2-12 ^ 2 = 225-144 = root of 81 = 9cm
Base AC = 9 + 9 = 18 cm
Answer a = 18cm
b) cos C = 9/15 = 0.6
Answer b = 0.6