## anonymous one year ago .

1. anonymous

|dw:1441573642078:dw|

2. anonymous

@freckles

3. iwillrektyou

n this case, you need the distance formula.

4. iwillrektyou

Those are ordered pairs, right? That show where each point is located?

5. anonymous

ya

6. iwillrektyou

Do you know the distance formula?

7. anonymous

sqrt of x2-x1 ^2+ y2-y2^2 pronounced y-1, not y ^2

8. iwillrektyou

Yes. So in order to find the area, you have to find the distance between the length and the width seperately. First, do (-5, 3), and (7, -6).

9. iwillrektyou

Just substitute and solve. Let me know if you need help.

10. anonymous

64+169

11. anonymous

want me to continue or something???

12. iwillrektyou

Yes. I will check your answers as you go, if you would like.

13. anonymous

233 now what???

14. iwillrektyou

You have to do the same thing with the points (-2, 7) and (-5, 3)

15. anonymous

81+64 145

16. iwillrektyou

In order to find the width. Then, you just multiply the 2. I will be checking your work,

17. anonymous

what do i do in order to find the width??

18. iwillrektyou

To find the width, use the distance formula for these 2 points: (-2, 7) and (-5, 3)

19. anonymous

yah wchich is 145

20. iwillrektyou

Yes. To find the area, just multiply the length and width together.

21. anonymous

um that's 33785 AAAANNNNDDD thats not an answer choice you are wrong

22. iwillrektyou

I am checking your work, and a step was done wrong.

23. iwillrektyou

For the width, it is 5.

24. iwillrektyou

And I am double checking my work for the length,

25. anonymous

how do you get 5??????

26. iwillrektyou

Ok so, Sqrt (-5 + 2)^2 + (3 - 7)^2 --> Sqrt (-3)^2 + (-4)^2 --> Sqrt (9 + 16) --> 5

27. anonymous

okay okaywhats the lenght

28. iwillrektyou

15

29. iwillrektyou

But do you understand the concept?

30. freckles

"Yes. So in order to find the area, you have to find the distance between the length and the width seperately. First, do (-5, 3), and (7, -6). " $\text{ distance between these two points is } \\ \sqrt{(-5-7)^2+(3-(-6))^2} \\ =\sqrt{(-5-7)^2+(3+6)^2} \\ =\sqrt{(-12)^2+(9)^2} .. \text{ so on ... }$

31. anonymous

yeah so 75

32. iwillrektyou

Yes. 75 is correct.

33. anonymous

can you help with one more?

34. iwillrektyou

I will try, but I am not very good at geometry, as I just started learning it. But shoot.

35. anonymous

|dw:1441574726192:dw| find the perimeter

36. anonymous

no i dont think so i think this has to do with the distance formula

37. iwillrektyou

Hmm..... I am not sure how to do this. Do they provide you with an ordered pair that substitutes for the variables?

38. anonymous

nope @freckles do you have any idea?

39. freckles

|dw:1441574975096:dw| the bottom we don't really have to use the distance formula for you know the distance from a to 0 is a and the distance from -a to 0 is a so the bottom length is just a+a=2a

40. freckles

|dw:1441575013692:dw| we have to use the distance formula for the other two sides though

41. anonymous

okay

42. anonymous

thank you guys so much for helping btw so what do we do now???

43. iwillrektyou

Sorry I couldn't help. I'm only in 8th grade. :(

44. anonymous

im in 8th too

45. iwillrektyou

46. freckles

distance formula for (-a,c) to (0,b) since that would be the length of that one side distance formula for (a,c) to (0,b) since that would be the length for that last side then just add all the lengths up to find the perimeter value

47. anonymous

can you help me in doing that?

48. freckles

what do you need help with exactly? entering in the values in to the formula?

49. anonymous

yeah just enter and then i'll solve

50. freckles

I will do one the distance from (-a,c) to (0,b) is: $\sqrt{(-a-0)^2+(c-b)^2} \\ \sqrt{(-a)^2+(c-b)^2} \\ \sqrt{a^2+(c-b)^2}$ you try finding the distance from (a,c) to (0,b) now..

51. anonymous

so would it be sqrt (a+a)^2+(c-c)^2?

52. freckles

are you using the points (a,c) and (0,b)?

53. freckles

the change of x is a-0 not a+a the change of y is c-b not c-c

54. anonymous

so sqrt (a-o)^2+(c-b)^2?

55. freckles

yes and a-0 is just a

56. freckles

|dw:1441575476337:dw| $\text{ so the distance between } (-a,c) \text{ and } (a,c) \text{ is } 2a \\ \text{ and the distance between } (a,c) \text{ and } (0,b) \text{ is } \sqrt{a^2+(c-b)^2} \\ \text{ and the distance between } (-a,c) \text{ and } (0,b) \text{ is } \sqrt{a^2+(c-b)^2}$ now just add up all 3 distances to find the perimeter

57. anonymous

so 2 sqrt (a^2+ (c-b)^2 +2a

58. freckles

yes: $2a+2 \sqrt{a^2+(c-b)^2}$

59. anonymous

60. anonymous

the answer choices are 2a sqrt a^2-(c-b)^2 or 2a sqrt a^2+(c+b)^2

61. freckles

$2a+2 \sqrt{a^2+(c-b)^2} \\ \text{ is the same as } 2a+2 \sqrt{a^2+(b-c)^2} \\ \text{ which is the same as } 2a+2\sqrt{(b-c)^2+a^2} \\ \text{ this is the same as } 2\sqrt{(b-c)^2+a^2}+2a \\ \text{ there is a lot of other ways \to express this }$

62. freckles

you can also factor out the 2... $2(\sqrt{(b-c)^2+a^2}+a)$

63. anonymous

but thats not even a choice

64. freckles

it is probably a choice but it is just written a bit different as I said there is a few different ways to express that same answer

65. anonymous

|dw:1441575733104:dw| these are my choices

66. freckles

67. anonymous

|dw:1441575827490:dw|

68. anonymous

that second one should be a plus 2a

69. freckles

yeah those answers are totally wrong I don't why they put the square root over everything like that

70. anonymous

it shouldn't be over the 2a sorry my bad

71. freckles

you do know when you asked me is this the answer I said yes... you wrote so 2 sqrt (a^2+ (c-b)^2 +2a and then I said "yes $2a+2 \sqrt{a^2+(c-b)^2}$" and I said yes assuming you meant to write a ) at the end of the (c-b)^2 there that is 2sqrt(a^2+(c-b)^2)+2a

72. freckles

addition is commutative 3+2 is the same as 2+3

73. freckles

$2a+2 \sqrt{a^2+(c-b)^2} \text{ is the same as } 2 \sqrt{a^2+(c-b)^2}+2a$

74. anonymous

sorry its late a night im really tire

75. anonymous

yah but thats still not an answer?

76. anonymous

im not talking about the 2a or the 2, look inside the sqrt. the answer has it as a^2-(c-b)^2 or a^2+(c+b)^2

77. freckles

both of those are wrong though

78. anonymous

well that's what they have as an answer....

79. freckles

well I don't know what you want me to tell you

80. freckles

recall the distance formula is: $\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$

81. freckles

do you see there is a plus between the two square parts?

82. freckles

and there is a minus in between the things inside the ( )

83. anonymous

yeah i get it that you are right i just don't know which one to pick

84. freckles

the ordered pairs were definitely (0,b) and (a,c) and (-a,c) right?

85. anonymous

yup

86. freckles

the only thing I can do is guess which one they meant as the right answer but either guess I make is going to be wrong whether it is marked right or not

87. anonymous

should i go with the plus or the minus?

88. freckles

let me confirm these are the choices: $2a+2 \sqrt{a^2-(c-b)^2} \\ 2a+2 \sqrt{a^2+(c+b)^2}$

89. freckles

there are no other choices?

90. freckles

like you can't pick a none of these?

91. anonymous

the only other choices are 6a and 9a

92. freckles

lol I don't know go with the -

93. freckles

94. anonymous

okay

95. anonymous

Anyone else have any ideas?

96. anonymous

@freckles i think i know what the answer is