GRE STUDY FORUM: GRE GEOMETRY QUESTION OF THE DAY

Sunday, January 27, 2008

GRE GEOMETRY QUESTION OF THE DAY

Side AB of triangle ABC is 80 cm long, whose parameter is 170 cm. If angle ABC = 60 degrees, shortest side of triangle ABC measures
a) 40 cm
b) 36 cm
c) 17 cm
d) 14 cm
e) 11 cm

8 comments:

Unknown said...: if u know the soln plz send it to me.; January 28, 2008 at 9:05 PM
deepak24gupta said...: use Cosine rule at angle B.

cosB = (a^2+c^2-b^2/2ac)

where angleB=60, c=80, take a=x, and
b = 90-x.(since perimeter = 170.)

ans. will be 17.; January 31, 2008 at 9:50 AM
Unknown said...: b is the answer; March 27, 2008 at 11:03 PM
Natural Dental Care said...: deepak could u explain im weak in maths
iving ge on 8th jul; March 27, 2008 at 11:25 PM
superindia said...: i couldn't; April 5, 2008 at 11:01 AM
deepak24gupta said...: Given angle B = 60 degree.
side c = 80 cm.
Perimeter = 170 cm.
let other two sides are 'b' and 'c'.
then a+b+c = 170
=>a+b+80 = 170
=>a+b = 90

let a = x, then b = 90-x.
Applying Cosine rule on angle B.
Cos B=(c^2+a^2-b^2)/2ac
=>1/2=((6400+ x^2-(90-x)^2)/2.x.80)
=>80 x = 6400+90.(2x-90)
=>80 x = 180 x - 1700
=>100 x = 1700
=> x = 17.; April 6, 2008 at 10:56 PM
Unknown said...: there must be some other way to solve this problem as ur way of solving may take more time.; May 7, 2008 at 1:28 PM
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