help with math word problem (pre-calculus)?

  • Thread starter Thread starter Cabbu
  • Start date Start date
C

Cabbu

Guest
The question asked:

A draw bridge is 160 feet long. The two sections of the bridge can be lifted upwar to an angle of 40 degree. If the water is 20 fet below the bridge, find the distance d between the end of a section and the water level when the bridge is fully open.

if you guys could provide me a step-by-step..it would be nice! i'm having a little difficult to solve with this..
 
The whole key to getting this problem is sketching a diagram. Once I drew the diagram, I could see the solution.

Draw a line to represent 160 ft bridge. Draw the sections open at 40° and label them 80ft. Drop a perpendicular from the end of the section down to the line of the bridge and label it "x". You now have a nice right triangle with the hypotenuse of 80 ft and an acute angle of 40°.

You can find "x" by using the sine function:
sin 40° = x/80
x = 80 sin 40° = approximately 51.423 ft.

distance d = 20 ft + 51.423 ft = approximately 71.423 ft.

that's it! ;)
 
Back
Top