Question

When the beam makes an angle of 40

Answer 1

A construction crew wants to hoist a heavy 
beam so that it is standing up straight. They 
tie a rope to the beam, secure the base, and 
pull the rope through a pulley to raise one 
end of the beam from the ground. When 
the beam makes an angle of 40 degrees with the 
ground, the top of the beam is 8 ft above 
the ground. 
Th e construction site has some telephone 
wires crossing it. Th e workers are 
concerned that the beam may hit the wires. 
When the beam makes an angle of 60 degrees with 
the ground, the wires are 2 ft above the top 
of the beam. Will the beam clear the wires 
on its way to standing up straight?

Math - Steve Thursday, April 16, 2015 at 6:22pmwe see that the length of the beam is 

8/sin40 = 12.45 ft 

At 60 degrees, the top is 

12.45sin60 = 10.78 ft high 

So, the wire is 12.78 ft up. 

Since the beam is only 12.45 ft long, it will not touch the wires.