Q. 175.0( 4 Votes )

If angles A, B, C of a ΔABC form an increasing AP, then sin B =
A. 1/2

B. √3/2

C. 1

D. 1/√2

Answer :

Let suppose A, B and C are the angles of a triangle ABC,


In ∆ABC,

A = (a – d)

B = a

C = a + d

Now, form an increasing A.P

As we know Sum of all the angle of a triangle is 180°,


A + B + C = 180°

(a – d) + a + (a + d) = 180°

3a = 180°

a = 180/3 = 60°

From the table,

sin B = sin A = sin 60°

= √3/2

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