## Dallasb22 3 years ago I need some help with Geometry, Finding Total Area in Prisms.

1. johnsonshelby

Si, si

2. johnsonshelby

What is the question?

3. Dallasb22

Find the Total Area of the Prism:

4. Dallasb22

5. Dallasb22

@johnsonshelby

6. johnsonshelby

Find the area of each side and add together... that's surface area I'm having a brain fart haha What is it you want to find?

7. Dallasb22

Thats gross.

8. Dallasb22

I want to find total Area

9. Dallasb22

T.A. = ph + 2B

10. johnsonshelby

Rho as in density, right?

11. Dallasb22

Rho?

12. johnsonshelby

Greek letter p

13. Dallasb22

perimeter of the base times height of the prism + 2Base = Total Area

14. johnsonshelby

Well the 2B part is easy. 2(area of the triangles)

15. Dallasb22

Area of Triangle : 1/2 times 9 "correct" ?

16. johnsonshelby

1/2 time base of the triangle times the height of the triangle. Because you are only given the base, you need to find the height.

17. Dallasb22

And to find the height we use pythag theorem correct?

18. johnsonshelby

So your new base would be 1.5 and the hypo would still be 3, yep

19. Dallasb22

So the height would be a^2?

20. johnsonshelby

c= 3, b=1.5, and yep a= a

21. johnsonshelby

so when you plug into pythag, you would get that

22. Dallasb22

So A= √6.75 ?

23. johnsonshelby

Yeah!

24. johnsonshelby

I have to get to my orgo class in 10 minutes, can you take it from here?

25. Dallasb22

So i find the area of the triangle and multiply it by 2 Then i add ?

26. johnsonshelby

add that to the (perimeter of the base x height), which would be (3+3+3)(6)

27. Dallasb22

Area of Triangle = 1.5√6.75 correct?

28. phi

btw, people would write $\sqrt{6.75}$ as $\frac{3 \sqrt{3}}{2}$

29. Dallasb22

Okay i got it. Thanks so much!! I just needed a refresh it's been awhile :)

30. Dallasb22

So it would be 4.5√3 / 2 @phi ?

31. phi

generally you don't mix decimals and fractions i.e. 4.5/2 If you have a multiple choice you probably would see the answer as a pure fraction $\frac{4}{9}\sqrt{3}$

32. phi

double that for the other triangle now you have 3 faces that all look the same size 3x6 3 faces each 18 = 54 plus the two triangles 8/9 sqrt(3)

33. Dallasb22

Other triangle?

34. phi

you have two triangles (the ends) and 3 "side faces" right?

35. Dallasb22