CBSE Class 12 Math 2020 Delhi Set 1 Solved Paper

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Section - C

Q. Nos. 27 to 32 carry 4 marks each.
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Question : 27
Total: 36
Solve for x:sin1(1x)2sin1(x)=
π
2
.
Given that sin1(1x)2sin1x=
π
2

let x=siny
sin1(1siny)2y=
π
2

sin1(1siny)=
π
2
+2y

1siny=sin(
π
2
+2y
)

1siny=cos2y
1siny=12sin2y as cos2y=12sin2y
2sin2ysiny=0
2x2x=0
x(2x1)=0
x=0,2x1=0
x=0,2x=1
x=0,x=
1
2

But x=
1
2
does not satisfy the given equation
x=0 is the solution of the given equation.
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