- A1 :
- B1 : 2
- C1 : 4
- D1 : 8
View written solutionFree
Correct answer: C
Step-by-step Solution
1. Find the intersection points of the circle and the parabola.
The given equations are:
- Circle: (1)
- Parabola: (2)
To find the intersection points, substitute equation (2) into equation (1): Factoring the quadratic equation: This gives two possible values for x: or .
- If , from equation (2), . This is not possible for real values of y.
- If , from equation (2), . This gives .
The intersection points are and .
- Point P is in the first quadrant, so .
- Point Q is in the fourth quadrant, so .
2. Find the point R (intersection of tangents to the circle with the x-axis).
The equation of the tangent to the circle at a point is . Here, .
- Tangent to the circle at :
To find the intersection point R with the x-axis, set : . So, the point R is . Note that the tangent at Q is , which also intersects the x-axis at .
3. Find the point S (intersection of tangents to the parabola with the x-axis).
The equation of the tangent to the parabola at a point is . For the parabola , we have , so . The tangent equation is .
- Tangent to the parabola at :
To find the intersection point S with the x-axis, set : . So, the point S is . The tangent at Q, , also intersects the x-axis at . A known property for a parabola is that the tangent at meets the x-axis at . Here , so the intersection is at , which confirms our result for S.
4. Calculate the ratio of the areas of and .
Both triangles, and , share the same base PQ. The base PQ is a vertical line segment along the line . The length of the base PQ is the distance between and , which is .
The area of a triangle is given by . Since the base PQ is common, the ratio of the areas is equal to the ratio of their corresponding heights.
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For , the vertex is . The base PQ lies on the line . The height of is the perpendicular distance from S to the line . Height.
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For , the vertex is . The base PQ lies on the line . The height of is the perpendicular distance from R to the line . Height.
Now, let's find the ratio of the areas:
The ratio of the areas of the triangles PQS and PQR is 1 : 4.
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