Question

Triangle ABC is equilateral. Find the length of CD.

Answer 1

@Kevin

Answer 2

equilateral that's means every side of the triangle has the same length.
assume side of triangle is n


Then we can find n using phytagoras formula :
9=sqrt(n^2-(1/2n)^2)
9 = sqrt(3/4 n^2)
81 = 3/4 n^2
n^2 = 108
n = 6 sqrt(3)

because CD is 1/2 n, then
CD = 1/2 * 6 sqrt(3) = 3 sqrt (3)

:)