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  1. In a ∆ ABC, ∠B = (π / 3) , ∠C = (π / 4) and D divides BC internally in the ratio 1 : 3 then sin (sin ∠BAD / sin∠CAD) is equal to
    1. 1
      2
    2. 1
      3
    3. 1
      6
    4. 6
Correct Option: C


∠B =
π
, ∠ =
π
34

and
BD
=
1
DC3

From ∆ ABD,
BD
=
AD
sin BADsin ABD

BD
=
AD
sin BADsin (π / 3)

BD
=
AD
sin BAD(√3 / 2)

⇒ AD =
3
.
BD
...(i)
2sin BAD

From ∆ ADC,
CD
=
AD
sin DACsin ACD

CD
=
AD
sin DACsin (π / 4)

⇒ AD =
1
.
CD
...(ii)
2sin DAC

From equations (i) and (ii),
3
.
BD
=
1
.
CD
2sin BAD2sin DAC


=
sin BAD
-
3
× √2 ×
1

sin DAC23

=
1
=
1
2 × √36



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