Geometry

prasanthkara
#1. April 3rd, 2007, at 6:59 PM.

(C) 80

Valmik
#2. April 4th, 2007, at 12:54 AM.

80

Jes
#3. April 4th, 2007, at 6:16 AM.

C

ankit
#4. April 4th, 2007, at 1:24 PM.

c

gmat_guy
#5. April 4th, 2007, at 5:24 PM.

How did you guys determine this?

Akanksha
#6. April 4th, 2007, at 5:55 PM.

Answer is “c” that is 80
to give answer to u “gmat_guy”…:
leave the middle triangle & concentrate on the side triangle which are 2 in no. so u’ll find that the base will be x/2 & height will be x (if u assume that the side of square is x cm)
then apply pythagorous theorem:
u’ll get
x2 +(x2/4)= 100
solve it u’ll get x2= 80 which is the required area..

pal
#7. April 4th, 2007, at 10:36 PM.

C

urefriendforever
#8. April 4th, 2008, at 9:43 AM.

just to elaborate on the explanation, in an isoceles triangle(which this one is), the median and the altitude are the same. so an altitude drawn from A to BC will intersect at the midpoint of the base BC..which is also mid point of one side of the square in this case.

Ans is 80

pranaysad
#9. April 4th, 2008, at 12:39 PM.

80

little star
#10. April 4th, 2008, at 8:19 PM.

sorry can someone explain what altititude means? I am from the UK …do you mean height? and what does median mean? Iare you using the pythagoras rule here? sorry I am confused how you derived the answered

smile
#11. April 4th, 2008, at 11:05 PM.

I dont understand how to work it out still- please would someone re-explain? how did you use the hypotenuse to calculate the base and square height?
thanks!!

Neelima
#12. April 4th, 2008, at 11:14 PM.

For sure answer is 80

daisy 2008
#13. April 5th, 2008, at 2:35 AM.

i got it!!! its 80
its not that hard its just understanding rules

Newbie
#14. April 5th, 2008, at 3:34 AM.

Draw a line perpendiculr to bc starting from A.
That is the height of the triangle ABC, name it h.
Also h= sides of the square.since ABC is an isoceles triangle that means A is the midpoint of ED, similarly O is the midpoint of BC.
Bo=OC=h/2 (o is the point where the perpendicular h meets on BC)

So using pythagoras Theorem:
h square=ab Square + BO sqaure
100= h square + h/2 square
solving this we get
400 = 5 h square
400/5 = h square
h square (also the area of a square) = 80.

I hope i helped.

So the answer is 80.

bri
#15. April 8th, 2008, at 12:22 PM.

c. 80

Richa
#16. April 8th, 2008, at 11:43 PM.

80

shelly
#17. April 9th, 2008, at 6:32 PM.

C 80

outer triangles would be congruent, A is mid point of side of triangle, also apply pythagorus and u get sq.(side/2) = 20; area = 20*4 = 80.

shelly
#18. April 9th, 2008, at 6:34 PM.

oops read above, A as mid point of side of square

Scott Ende
#19. April 21st, 2008, at 6:51 PM.

How do you solve the equation
x2+1/2×2=100 ??

your mom
#20. April 23rd, 2008, at 11:59 AM.

Newbie I got u til about here….

100= h square + h/2 square
solving this we get

HERE I LOST U….
400 = 5 h square
400/5 = h square
h square (also the area of a square) = 80.

sumanth toom
#21. April 23rd, 2008, at 3:56 PM.

“That is the height of the triangle ABC, name it h.
Also h= sides of the square.since ABC is an isoceles triangle “

kv
#22. April 23rd, 2008, at 6:51 PM.

100 = h^2 + (h/2)^2

we get h^2 = 80

Nrip Nihalani
#23. May 2nd, 2008, at 3:32 PM.

let the side of the square be x and the area be Y = x^2
Now from the figure
x^2 + (x/2)^2 = 10^2
x^2 + (x/2)^2 = 100

Thus
Y + Y/4 = 100
5Y = 400
Y = 80

Thus C

PV
#24. May 5th, 2008, at 11:31 AM.

the answer is 80

Ritula
#25. May 5th, 2008, at 7:06 PM.

answer is C

jaspreet cheema
#26. May 10th, 2008, at 1:36 AM.

Answer is C

Navya
#27. June 3rd, 2008, at 11:11 AM.

Ans is C - 80

mag
#28. July 28th, 2008, at 1:31 AM.

c