PQ is the double ordinate of the parabola y2 = 4x which passes through...
let the circumcenter of trapezium be T(n, 0)
Then PT = PB
or n = 7
radius √40 = 2 √10
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PQ is the double ordinate of the parabola y2 = 4x which passes through...
To find the circumradius of trapezium PBCQ, we need to first understand the properties of the given parabola and the triangle PQA.
Properties of the Parabola:
- The equation of the parabola is given as y^2 = 4x, which is a standard form of a parabola.
- The vertex of the parabola is at the origin (0,0) and the focus S lies on the positive x-axis.
- The distance from the vertex to the focus is called the focal length, which is given by the equation F = a, where 'a' is the distance from the vertex to the directrix.
- The directrix is a line perpendicular to the x-axis and equidistant from the vertex.
- The point P lies on the parabola and is the double ordinate, meaning its y-coordinate is twice the x-coordinate.
- The point S lies on the parabola and is the focus.
Properties of Triangle PQA:
- Triangle PQA is an isosceles right-angled triangle, where A lies on the axis of the parabola.
- Let the coordinates of point A be (a, 2a), where 'a' is a positive real number.
- The slope of the line PA can be calculated as (2a-0)/(a-0) = 2.
- The equation of the line PA can be written as y = 2x.
Finding Points B and C:
- To find the coordinates of point B, we substitute y = 2x in the equation of the parabola: (2x)^2 = 4x, which simplifies to x = 0 or x = 2.
- When x = 0, y = 0, so point B is (0, 0).
- When x = 2, y = 4, so point C is (2, 4).
Finding Point Q:
- Since point Q lies on the parabola, we can substitute the coordinates of Q (x, y) in the equation of the parabola: y^2 = 4x.
- Since Q lies on the line PA (y = 2x), we can substitute y = 2x in the equation of the parabola: (2x)^2 = 4x.
- Simplifying the equation, we get x = 2 or x = 0.
- When x = 2, y = 4, so point Q is (2, 4).
- When x = 0, y = 0, so point Q is (0, 0).
Finding the Circumradius of Trapezium PBCQ:
- The circumradius of a trapezium is the radius of the circle passing through all four vertices.
- The vertices of trapezium PBCQ are P(0, 0), B(0, 0), C(2, 4), and Q(2, 4).
- The distance between any two points can be calculated using the distance formula: d = sqrt((x2 - x1)^2 + (y2 - y1)^2).
- The distance between P and C is d1 = sqrt((2-0)^2 + (4-0)^2) = sqrt(20).
- The distance between B and C is d2
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