## sammy12 Group Title A solid candy jawbreaker is cut in half. If its diameter is 4 cm, what is the surface area of a half piece? please show me the steps. 2 years ago 2 years ago

1. beth1127 Group Title

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2. sammy12 Group Title

i am getting 8 pi .is it right

3. Tonik Group Title

i think it should be 48pi

4. Tonik Group Title

oh hell, no.... i thought radius was 4, not diameter... sec

5. sammy12 Group Title

answer is 12 pi.I don't know how

6. funinabox Group Title

2A = 4pi*r^2 2A = 4pi*(2)^2 2A = 16pi A = 8pi I set it equal to 2A because we want half the surface area, I found the full SA then divided by 2.

7. sammy12 Group Title

i am getting 8 pi

8. Tonik Group Title

the surface area on the outside is 8pi, you're correct, but you need to add the surface are where the cut was made (basically the area of a circle radius 4

9. Tonik Group Title

10. Tonik Group Title

so its 12pi

11. sammy12 Group Title

12. funinabox Group Title

Ahhh yes I forgot about the inside cut. I assumed a hollow sphere. :O stupid mee

13. Xishem Group Title

It's the surface area of half a sphere plus the surface area of the circle... $\frac{4πr^2}{2}+\pi r^2=2 \pi r^2+\pi r ^2=3 \pi r^2= 3 \pi (2cm)^2=12 \pi\ cm$

14. Xishem Group Title

*$12\pi\ cm^2$

15. sammy12 Group Title

Thanks