Q.

Let ABCD be a trapezium whose vertices lie on the parabola y2=4x. Let the sides AD and BC of the trapezium be parallel to y-axis. If the diagonal AC is of length 254 and it passes through the point (1, 0), then the area of ABCD is          [2025]

1 252  
2 1258  
3 754  
4 758  

Ans.

(3)

Let A(at12,2at1) and C(at12,–2at1) be the points lies on parabola y2=4x.

∴   Length of AC=a(t1+1t1)2=254 (Given)

⇒ t1+1t1=±52

So, A(14,1), B(4, 4), C(4,–4) and D(14,–1)

∴   The area of trapezium ABCD = 12(8+2)(4–14)=754.