+2 votes
in JEE by kratos

Points D, E are taken on the side BC of a triangle ABC such that BD = DE = EC. If ∠BAD = x, ∠DAE = y, ∠EAC = z, then the value of sin(x + y)sin(y + z)/sin x sin z is equal to

(A) 4

(B) 1

(C) 2

(D) of these

1 Answer

+5 votes
by kratos
 
Best answer

Correct option**(A) 4**

See Fig. From ∆ADC

sin(y + z)/DC = SinC/AD .....(i)

From ∆ABD sinx/BD = sinB/AD .....(2)

and from ∆AEC, sinz/EC = sinC/AE .....(3)

Also, from ∆ABE, sin(x + y/BE) = sinB/AE .....(4)

From Eqs. (1), (2), (3) and (4), we get

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