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Geometry Problem

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Source: — Problem Solving |

by Anurag@Gurome » Tue Oct 16, 2012 8:46 pm
Mjkourtis wrote:The perimeter of an isosceles right triangle is 16+ 16 sqrt(2). What is the hypotenuse?
A. 8
B. 16
C. 4 sqrt(2)
D. 8 sqrt(2)
E. 16 sqrt(2)
Let the sides of triangle be x, x, and sqrt2*x.
2x + sqrt2*x = 16+16*sqrt2.
x(2 + sqrt2) = 8*sqrt2(2 + sqrt2).
x = 8*sqrt2.
Hypotenuse is x* sqrt2 = 8*sqrt2*sqrt2 = 16

The correct answer is B.
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by GMATGuruNY » Wed Oct 17, 2012 2:27 am
The perimeter of a certain isosceles right triangle is 16 + 16√2. What is the length of the hypoteneuse?
a. 8
b. 16
c. 4√2
d. 8√2
e. 16√2

OA is b.
Could someone please explain this answer?
thanks
The sides of an isosceles right triangle are proportioned: s : s : s√2.
So if s=side and h=hypotenuse, then h = s√2 and s = h/√2.

We can plug in the answers, which represent the hypotenuse.

Answer choice C: h = 4√2
s = (4√2)/√2 = 4.
p = 4 + 4 + 4√2 = 8 + 4√2.
Eliminate C. The perimeter needs to be quite a bit larger.

Answer choice B: h = 16
s = 16/√2 = (16*√2)/(√2*√2) = (16√2)/2 = 8√2.
p = 8√2 + 8√2 + 16 = 16 + 16√2. Success!

The correct answer is B.
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by AIM TO CRACK GMAT » Wed Oct 17, 2012 6:49 am
Mr. Anurag... Could u once again plzz xplain the same question in a slightly different manner? Guru Ny ... Your method is good
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by anuprajan5 » Wed Oct 17, 2012 8:08 am
Hi,

The ratio of sides of a right isosceles triangle will be in √2:√2:1 form where the angles facing these will be in 45:45:90 form.

By that logic, the sides to me should be 16, 8√2 and 8√2.

Therefore the hypotenuse - the longest side is 16

Answer B

Regards
Anup
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