please help

A triangle which meaures 100 feet on each side find the height

Three equal angles if three equal sides.

They must add to 180
so all are 60 degrees.
half of base = 50
altitude up from there = h
right triangle, 30 60 90
h^2 + 50^2 = 100^2
h^2 = 10,000 - 2,500
= 7,500
h = 10 sqrt (75) = 10 sqrt (25*3) = 50 sqrt 3