1. anonymous

2. anonymous

3. anonymous

can someone explain how to do it and not just give me the answer please

4. anonymous

@mathstudent55

5. anonymous

circumference of a semicircle: (1/2) x pi x d where d is the diameter

6. anonymous

so what is the diameter of the semicircle?

7. ybarrap

What is r here? That's that's the hardest part of the problem. |dw:1434406738797:dw|

8. ybarrap

What is the relationship between r and 3 ?

9. ybarrap

|dw:1434406911440:dw|

10. ybarrap

So the answer is $$\pi\times r$$. So all you need to find is r. Any guesses?

11. anonymous

oh sorry i was eating let me look

12. anonymous

@ybarrap well 2 x pi is 6.28

13. anonymous

i still dont know how to find r im sorry im bad at this

14. ybarrap

|dw:1434407560400:dw|

15. ybarrap

Do you see that what r is now?

16. anonymous

ohhh

17. anonymous

yes!

18. anonymous

19. ybarrap

What is r?

20. anonymous

3 i think

21. anonymous

or 1.5

22. ybarrap

Yes! So the answer is ....

23. anonymous

9.42 ft

24. ybarrap

$$\pi\times r$$, which is half the circumference of a circle with a radius of r

25. ybarrap

you know $$\pi$$ and you know r - just multiply

26. anonymous

ohhh it's 4.71?

27. ybarrap

Yes!

28. anonymous

okay, thank you so much for your help! :-)