Q.

In a △ABC, Suppose y = x is the equation of the bisector of the angle B and the equation of the side AC is 2x – y = 2. If 2AB = BC and the points A and B are respectively (4, 6) and (α,β), then α+2β is equal to          [2024]

1 39  
2 42  
3 48  
4 45  

Ans.

(2)

We have, y = x          ... (i)

and    2x – y = 2          ... (ii)

Solving (i) and (ii), we get x = 2 and y = 2

As, △ABD =~ △CBD

∴   ABBC = ADDC = 12

D (λ + 83, 2λ - 2 + 123) lies on y = x

∴   λ + 83 = 2λ + 103   ⇒   λ = -2. So, C≡ (-2, -6)

The image of the point A will lies on the line BC.

Let A' = (6, 4)

Now, β - 4α - 6 = 108   ⇒   α - 4α - 6 = 54   (∵   α = β)

⇒   4α - 16 = 5α - 30  ⇒  14 = α = β

∴   α + 2β = 14 + 2 × 14 = 42