Golf Distance Finder Precalculus

[jaredld]

I can't seem to figure this problem out. If somebody could explain to me how to get the answer I would appreciate it.

GOLF DISTANCE FINDER: A device used in golf to estimate the distance d, in yards, to a hole measures the size s, in inches, that the 7-ft pin appears to be in a viewfinder. Express the distance d as a function of s.

As far as I can tell what I get out of this problem is we have the base of a triangle d (the base would be 1/3d if you put it in relation to feet) and a leg of the triangle 7 feet (or 84 inches) so 7^2+d^2=C^2. Also acording to the picture in the book, the vertex of the triangle is at the eye. The device is exactly 6 inches from the eye where the flag fills the view finder.

What I dont understand is where in the heck the six inches away from the face came from. Is that the size of the 7 foot flagpole at d or what?

The answer is d(s)=14/s someone please explain, or atleast tell me that the creator of my precalculus book is a retard. It would make me feel better.

 

[soroban]

Hello, jaredld!

I have a different diagram . . .

GOLF DISTANCE FINDER
A device used in golf to estimate the distance d, in yards, to a hole measures the size s, in inches,
that the 7-ft pin appears to be in a viewfinder.
Express the distance d as a function of s.

The wording is pretty bad, but I think I get what they're saying.

The hole is a distance d (inches) from the eye.
. . There is a 7-foot (84-inch) pole there.

The device is held to the eye.
. . On a screen, 6 inches from the eye, the image of the pole is s inches high.

                                 *
                           *     |
                     *           |
               *                 |
         *     |                 |84
   * . . . . . |s. . . . . . . . | 
         *     |                 |
    <--------->*                 |
         6           *           |
                           *     |
                 d               *
   <---------------------------->

We have similar isosceles triangles.

. . . . . . . .d . . . . .6 . . . . . . . . . . . . . .504
Hence: . --- . = . --- . . ---> . . d . = . ------ .inches
. . . . . . . 84 . . . . s . . . . . . . . . . . . . . .s

. . . . . . . . . . . . . . .14
Therefore: . d .= . ---- .yards
. . . . . . . . . . . . . . . s

 

[jaredld]

DOOOOOH! Thanks. I almost got it, but the 14 yards thing threw me off. I appreciate it very much.