Question

A ladder 8m long reaches a point 8m below
thee top of a vertical flagstaff. From the foot of the ladder, the angle of elevation of the top of the flagstaff is 60 degrees. Find the length of the flagstaff

Answer 1

Answer:

CD=AD=9m

∵△ACD is isosceles.

∠CAB=60°

∴∠ACB=∠CAD=30°

∴∠BAD=30°

In △ABD,

sin30°=

AD

BD

⇒BD=ADsin30°=4.5

Therefore,

BC=BC+DC=4.5+9=13.5m