ABCD is the floor. By pathagoras
AC2 = 144 + 81 = √225
AC = 15cm
Height of room 8m, diagonal of floor is 15m
Therefore, the cosine of the angle which a diagonal of the room makes with the floor is
EC2 = 152 + 82 cosine
adjHyp=1517
EC2 = √225+64
EC = √289
= 17
