cos(sin inverse x) = 1/9
solve it
RoshanSingh1:
but not i
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Here is the solution... Ahhh yessiirr!!
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At first we simplify for Cos(Sin-1 x) -
Let, Sin-1X = y, then X = Sin y
Now putting the value of X in Cos(sin-1x), we get -
Cos{sin-1(siny)} = cos y ----- (i)
Again, we know that,
Sin2y + Cos2y = 1
or Cos2y = 1 – sin2y
or Cos y = ( 1 – sin2y)1/2 ----------- (II)
From (i) and (II),
Cos{sin-1(siny)} = (1-sin2y)1/2
or, Cos (sin-1 x) = ( 1 – x2)1/2
Now, cos(sin-1 x) = 1/9
or, ( 1 – x2)1/2 =1/9
or, (1-x2) = 1/ 81
or, X2 = 1 – 1/81
or, X2 = 80/81
or, x = ? ( solve it)
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