## waheguru 4 years ago need some help im getting 311

1. anonymous

ok

2. anonymous

???

3. karatechopper

311?

4. waheguru

im posting the question sorry

5. waheguru

6. waheguru

here we are

7. anonymous

Do you have the formula for the surface area of a cylinder?

8. waheguru

2pirsq plus 2pirh

9. anonymous

Surface area of fully cylinder = circumference * length. Here, you have half of it. So, 1/2*circumference*length = 1/2 * pi * 6 * 30 = 90 * pi

10. anonymous

a.

11. anonymous

waheguru - that is when including bottom and top circles. In this case, the roof has no such thing. So, you just need 1/2 circumference * length.

12. asnaseer

@GT is right

13. waheguru

oh so i included the bottom???

14. anonymous

Yeah. Don't.

15. waheguru

k so this is what i did 2 x pi x 3^2 + 2 x pi x 3 x 30 and divide by 2

16. anonymous

hi

17. anonymous

Remove 3*pi*r^2 and the rest is good.

18. waheguru

y

19. anonymous

a. is right sure

20. anonymous

Because the roof does not have a base and top (according to the problem description).

21. asnaseer

the question is asking for the area of the roofs curved surface - that does not include the two ends of the greenhouse

22. waheguru

so just the lateral

23. anonymous

yes.

24. waheguru

thx brozz

25. asnaseer

the curved surface of a cylinder has a surface area of $$2\pi rh$$. in this case you have half a cylinder, so the surface area becomes $$\pi rh$$

26. anonymous

HI GUYS

27. waheguru

just practising for grade 9 EQAO

28. asnaseer

what is EQAO?

29. waheguru

evil questions attacking ontario lol im kidding its like an exam for grade 9 students

30. asnaseer

lol! :-D - good luck with them...

31. waheguru

thx

32. anonymous

is half perimeter of base multiply lenght=surface area

33. anonymous

this very easy

34. asnaseer

@jhonyy9 - things are always easy when you know how to do them - try and recall the days when you were also at the lower end of the learning curve :-)

35. asnaseer

like we ALL were

36. anonymous

yes right but this is the same like a rectangle curved on the base