Math Problem Statement
A circle is centered at $O.$ The tangent to the circle at $P$ is extended to $Q.$ Line segment $\overline{QS}$ intersects the circle at $R.$ Find the area of the circle.
[asy] unitsize(2.5 cm);
pair A, B, C, D, E, F, G, O;
A = dir(70); B = A + 1.2dir(-20); C = dir(25); D = 2C - B; O = (0,0);
draw(Circle(O,1)); draw(A--B--D--O);
dot("$P$", A, N); dot("$Q$", B, dir(0)); dot("$R$", C, SW); dot("$S$", D, NW); dot("$O$", O, SW); label("$3$", (D + O)/2, NW, red); label("$4$", (C + D)/2, S, red); label("$4$", (B + C)/2, S, red); label("$8$", (A + B)/2, N, red); [/asy]
Solution
We are given a circle centered at , with a tangent at point . The tangent is extended to point , and line segment intersects the circle at point . We are tasked with finding the area of the circle.
Step 1: Analyze the diagram
The diagram provides the following key information:
- is the radius of the circle, as lies on the circle and is perpendicular to the tangent at .
- , which is the length of the tangent from to .
- The segment is extended and intersects the circle at .
- The segment , where the distances are the sum of the two smaller segments and .
Step 2: Apply the Power of a Point Theorem
The Power of a Point Theorem states that the power of point with respect to the circle is equal to the product of the lengths of the segments of the line that intersects the circle. Specifically, the theorem gives:
From the problem:
- The radius , which is what we need to find.
Step 3: Set up the equation
Using the Power of a Point Theorem, we substitute the known values:
This simplifies to:
Step 4: Solve for
To find the radius , take the square root of both sides:
Step 5: Calculate the area of the circle
The area of a circle is given by the formula:
Substitute :
Thus, the area of the circle is .
If you'd like further details or have any questions, feel free to ask! Here are some related questions:
- How does the Power of a Point Theorem work for tangents to a circle?
- What is the geometric significance of the length of a tangent from a point outside the circle?
- Can we apply the Power of a Point Theorem in other geometric configurations? Provide examples.
- How do we calculate the area of a circle if we know the length of a chord and its perpendicular distance from the center?
- What other properties of tangents to circles can help solve geometric problems?
Tip: In geometry, understanding the properties of tangents and secants to a circle can significantly simplify the solution process for many problems involving circles!
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Math Problem Analysis
Mathematical Concepts
Geometry
Circles
Tangents
Power of a Point Theorem
Formulas
Power of a Point: QP * QS = OP^2
Area of a Circle: A = \pi r^2
Theorems
Power of a Point Theorem
Properties of Tangents to a Circle
Suitable Grade Level
Grades 9-11
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