## A community for students. Sign up today

Here's the question you clicked on:

## KimJaFo one year ago Jason designed an arch made of wrought iron for the top of a mall entrance. The 11 segments between the two concentric circles are each 1.25 m long. Find the total length of wrought iron used to make the structure. Round the answer to the nearest meter. Show your work. I need some hwlp with this, Ill try and post the picture in the comments

• This Question is Closed
1. KimJaFo

2. KimJaFo

@jagr2713 Could you help?

3. anonymous

so we have 11 segments of 1.25 m each a semicircle with a diameter of 15 m and a semicircle with diameter (15 - 1.25 - 1.25) m|dw:1438747266213:dw|

4. anonymous

let's just add up the lengths. The circumference of a circles is πd, so for a semicircle it's $C=\frac{ \pi d }{ 2 }$

5. anonymous

Find the circumference for the 15 m semicircle using that formula

6. KimJaFo

Thanks!

7. KimJaFo

So, the formula, once I plug in everything, would be C = pi15/2?

8. anonymous

yes, but we write 15pi/2. Then do the same with the smaller semicircle

9. KimJaFo

What do you mean? I'm kinda getting a lil confused. Sorry '-'

10. anonymous

they're asking for the total length of all the lines/curves in the picture. 15π/2 is just the top semicircle. We also have to account for the bottom semicircle and all 11 line segments between them.

11. anonymous

Does that make sense?

12. KimJaFo

A little bit, let me try it.

13. anonymous

to find the diameter of the smaller circle, subtract the 1.25 m on each end from the diameter of the larger. d = 15 - 2(1.25) = 12.5 m So use 12.5 in the circumference formula to get the length of this part

14. KimJaFo

how?

15. anonymous

C = πd/2 where d = 12.5

16. KimJaFo

Ah ok, thank you

17. anonymous

|dw:1438748775575:dw|

18. anonymous

The last thing you have to find is the length of the segments. There are 11 and the are each 1.25 m. What's the total length?

19. KimJaFo

I think I got it, thank you

20. anonymous

you're welcome

#### Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy