OpenStudy (anonymous):

# A 5-foot tall student stands 10 feet away from the lens of a camera. The film of the camera is 3 inches away from the lens. A 5 ft tall student is standing 10 feet away from the lens of a camera; behind the lens of the camera is shown the film of the camera, 3 inches away from the lens. What is the height of the film? Answer 0.2 inches 0.7 inches 1.2 inches 1.5 inches

6 years ago
hero (hero):

Was there a picture included with this?

6 years ago
OpenStudy (anonymous):

yes. one second

6 years ago
OpenStudy (anonymous):
6 years ago

hero (hero):

What exactly is the topic of study for your class?

6 years ago
OpenStudy (anonymous):

meaning? Its geometry and that lesson was about similar triangles

6 years ago
hero (hero):

That's what I needed to know

6 years ago
OpenStudy (anonymous):

kk

6 years ago
hero (hero):

Okay, I figured out what it was, but the explanation is kind of whacky

6 years ago
hero (hero):

You're supposed to create a proportion relating the two triangles by setting height of the person to the height of the film equal to the length of the person from the lens to the length of the film from the lens.

6 years ago
OpenStudy (anonymous):

right. I can get there but whats next?

6 years ago
OpenStudy (anonymous):

do I cross multiply?

6 years ago
hero (hero):

Next you cross multiply, then solve for x.

6 years ago
hero (hero):

wait a second....

6 years ago
hero (hero):

We need to convert feet to inches.

6 years ago
OpenStudy (anonymous):

oh lord. I didnt notice that......

6 years ago
hero (hero):

Yeah, I just realized it myself.

6 years ago
OpenStudy (anonymous):

1/40 = 5/x ??

6 years ago
OpenStudy (anonymous):

x = 200.........right?

6 years ago
hero (hero):

So after converting ft to inches, you get 60 for the height of the person 120 the person's distance from the lens So replacing those in the proportion you get: \[\frac{60}{x}=\frac{120}{3}\]

6 years ago
OpenStudy (anonymous):

Just kidding! geez my brain is fried

6 years ago
hero (hero):

\[\frac{60}{x}=40\]

6 years ago
hero (hero):

60 = 40x 6 = 4x 6/4 = x 2/3 = x

6 years ago
hero (hero):

in inches, not feet

6 years ago
OpenStudy (anonymous):

60/x = 40 x = 40/60 x = 4/6 x = 2/3 x = .67?

6 years ago
hero (hero):

Yes

6 years ago
OpenStudy (anonymous):

.7 inches. Yay!! thank you!

6 years ago
hero (hero):

wait, lol

6 years ago
OpenStudy (anonymous):

uh oh.......lol

6 years ago
hero (hero):

I think I did that backwards

6 years ago
hero (hero):

3/2 = x

6 years ago
hero (hero):

60 = 40x 6 = 4x 6/4 = x 3/2 = x

6 years ago
OpenStudy (anonymous):

1.5??

6 years ago
hero (hero):

Yes

6 years ago
OpenStudy (anonymous):

thanks!

6 years ago
hero (hero):

Funny thing is, even if you don't convert, you still get 1.5 I find that very strange

6 years ago
OpenStudy (anonymous):

ha

6 years ago
hero (hero):

lol

6 years ago