Question 1154552

TAN (45) =MC /CE

MC = CE ( tan 45 =1)

tan 60 = MC/CD
{{{sqrt(3)}}} = MC/CD

                = CE/CD
*[illustration tunnel.png].
CD = CE/ sqrt(3)

sqrt(3) *CD = CE

1.73CD= CD+DE
0.73CD =80

tan 30 = 1/sqrt(3) =MC/AC

AC = MC * sqrt(3)
= 189.6*1.73
=328
BC = 328-120 =208

Length of tunnel =208 +110=318 m