posted by Jess D .
The altitude of an equilateral triangle is 12cm. Find the length of the sides.
You know the angles of an equilateral triangle are 60º each.
The altitude will form a right-angles triangle with angles 30,60,90º
the lengths of those sides could be 1,√3, and 2
so by ratios:
x/2 = 12/√3
x = 24/√3 = 13.856
sin 60 = 12/x
x = 12/sin60 = 13.856