Consider a circle inscribed in a square. A rectangle with a base of 2 cm and a height of 1 cm is inserted in the space between one of the vertices of the square and the circumferen... Consider a circle inscribed in a square. A rectangle with a base of 2 cm and a height of 1 cm is inserted in the space between one of the vertices of the square and the circumference in such a way that one vertex of the rectangle coincides with that of the square and the opposite vertex lies on the circumference. Calculate the radius of the circle.

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Understand the Problem

The question describes a circle inscribed in a square, with a rectangle placed in the corner. The goal is to calculate the radius of the circle given the dimensions of the rectangle.

Answer

A) 5 cm
Answer for screen readers

A) 5 cm

Steps to Solve

  1. Visualize the problem Draw a diagram of the square, inscribed circle, and rectangle. Label the radius of the circle as $r$. The center of the circle is at $(r, r)$ if we set the lower left corner of the square as the origin $(0, 0)$.

  2. Identify the coordinates of the rectangle's outer vertex The vertex of the rectangle that lies on the circumference of the circle has coordinates $(2, 1)$.

  3. Use the circle equation The equation of the circle is $(x - r)^2 + (y - r)^2 = r^2$.

  4. Plug in the coordinates of the point (2, 1) Since the point $(2, 1)$ lies on the circle, we have $(2 - r)^2 + (1 - r)^2 = r^2$.

  5. Expand and simplify the equation Expanding the equation, we get $4 - 4r + r^2 + 1 - 2r + r^2 = r^2$. Simplifying, we have $r^2 - 6r + 5 = 0$.

  6. Solve the quadratic equation We can solve this quadratic equation for $r$. Factoring gives us $(r - 5)(r - 1) = 0$. So, $r = 5$ or $r = 1$.

  7. Choose the correct solution Since the rectangle has a base of 2 and a height of 1, the radius must be greater than 2. Therefore, $r = 5$.

A) 5 cm

More Information

The radius of the circle is 5 cm. This problem involves geometric visualization and algebraic manipulation to solve for an unknown radius.

Tips

A common mistake is choosing the wrong root of the quadratic equation and including $r=1$ in the possible answers. Always think about the geometric context when solving the problem.

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