1ha lekin kaise ??
let S1, S2......... be the squares such that for each n≥1, the length of a side of Sn equals the length of a diagonal of sn+1. if the length of a side of S1 is 10cm, then for which of the following values of n is the area of Sn less than 1sq.cm ?
a) 7
b) 8
c) 9
d) 10
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9 Answers
62Arrey I gave this question just 2 days back.. this is a jee past question..
yes the answer is 8
asis has replied just a couple of days back..
11the sides of the squares form an decreasing gp..... a=10 and r=1/√2
if an is side of nth square,
Area= (an)2
thus the area will form a decreasing gp of their own with a=100 and r= 1/2....
An<1
a.rn-1<1
(1/2)n-1<1/100
2n-1>100
But 26 is less than 100 => n-1 > 6 ==> n>7
PLS DON'T PINK ME....I FOUND OUT THE MISTAKE AND THEN CHANGED THE ANSWER....
1The answer is 8,9,10
side of nth square an=10/(√2)n-1
Area of nth square = 100/2n-1
Therefore n=8