When the beam makes an angle of 40

degrees with the ground, the top of the

beam is 8 feet above the ground

 There are telephone

wires nearby and the

workers are worried that

the beam may hit the

wires Will it?

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.