## anonymous 4 years ago What is the surface area of the composite figure? ~Attachment in comments~

1. anonymous

2. Shane_B

Take it in pieces and sum up the values at the end. It's going to be:$SA_{bottom}+4SA_{side}+4SA_{triangle~side}$

3. Shane_B

If you're stumped on this let me know and I'll walk you through it.

4. anonymous

It would help if you could walk me through it, please?

5. Shane_B

Ok, the bottom of the figure is a square with 6mm sides right? Well, the SA of a square is just side*side: $6mm*6mm=36mm^2$

6. Shane_B

The sides are rectangles so it's basically SA = LW:$7mm*6mm=42mm^2$

7. Shane_B

The top parts are just triangles with a 6mm base and a height of 4mm. The SA of a triangle is (1/2)bh:$\frac{(6mm)(4mm)}{2}=12mm^2$

8. Shane_B

Now use the first equation I posted which sums it all up to get the total surface area. If you work it out I'll double-check your answer.

9. anonymous

For some reason I've got 90 mm^2 but that's not even close to one of the answers I have :/

10. Shane_B

I think I lost you...here:$SA_{total}=SA_{bottom}+4SA_{side}+4SA_{triangle~side}$$SA_{total}=36+4(42)+4(12)=?$

11. Shane_B

There's no magic formula when doing these types of problems. You just take the individual areas and sum them up at the end.

12. anonymous

252 mm^2?

13. Shane_B

Yes

14. anonymous

Thank you!

15. Shane_B

yw, good luck :)

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