Answer:
169 m
Step-by-step explanation:
See the image below.
Line AB represents the monument and line BC its shadow
Line DB represents the man and Line BE it shadow.
The Sun’s rays are parallel, so AC||DE.
Then ∆ABC ~ ∆DBE
AB:BC::DB:BE
x/65.8 = 1.8/0.7 Multiply both sides by 65.8
x = 65.6 × 1.8/0.7
x = 65.6 × 2.571
x = 169 m
The height of the Washington monument is 169 m.