Circle Geometry Problem Setup
We are given a circle with a chord of length $20\text{ cm}$ and the distance from the center to this chord is $15\text{ cm}$. We need to find the approximate radius of the circle.
- Chord length $l = 20\text{ cm}$.
- Distance from center $d = 15\text{ cm}$.
The radius, the distance from the center to the chord, and half the chord length form a right-angled triangle. The radius is the hypotenuse.
Calculating Radius Using Pythagorean Theorem
First, find half the length of the chord:
Half chord length $= \frac{l}{2} = \frac{20\text{ cm}}{2} = 10\text{ cm}$.
Let the radius be $r$. According to the Pythagorean theorem ($a^2 + b^2 = c^2$), where $a$ and $b$ are the legs and $c$ is the hypotenuse:
In our triangle:
- One leg is the distance from the center, $d = 15\text{ cm}$.
- The other leg is half the chord length, $\frac{l}{2} = 10\text{ cm}$.
- The hypotenuse is the radius, $r$.
So, the equation becomes:
$r^2 = d^2 + \left(\frac{l}{2}\right)^2$Substitute the values:
$r^2 = (15\text{ cm})^2 + (10\text{ cm})^2$ $r^2 = 225\text{ cm}^2 + 100\text{ cm}^2$ $r^2 = 325\text{ cm}^2$Finding the Approximate Radius
To find the radius $r$, take the square root of $325$:
$r = \sqrt{325}\text{ cm}$We know that $18^2 = 324$. Since $325$ is very close to $324$, the value of $\sqrt{325}$ will be slightly more than $18$.
$r \approx 18.03\text{ cm}$The approximate radius of the circle is $18\text{ cm}$.
Similar Questions
- A circle that has a radius of 5 centimeters, and there is a chord measuring 8 centimeters in length. What is the distance from the center of the circle to the chord?
- A circle of radius of 12 cm, two radii are drawn such that the length of the chord connecting their endpoints is 12 cm. What is the area of the minor segment formed?
- The line segment from the center of a circle to the midpoint of a chord is 10 cm long. If the radius is 26 cm, what is the length of the chord?
- A chord of a circle subtends an angle of 60° at the center. What is the angle subtended at a point on the circle in the same segment?
- A tangent is drawn to a circle with a radius of $5\text{ cm}$. At the point of tangency, what is the angle between the tangent and the radius?
- The radii of three concentric circles are in arithmetic progression. If the innermost radius is 7 cm and the outermost is 21 cm, what is the radius of the middle circle?
- If a chord subtends an angle of $75^{\circ}$ at the center, the angle it subtends at the circumference on the same side is:
- A chord subtends an angle of 70° at the center of a circle. What is the measure of the angle subtended by the same chord at any point on the remaining part of the circle?
- Chord AB and chord CD are equal and subtend angles of $50^\circ$ and $x^\circ$ at the center respectively. Find $x$
- A chord is drawn in a circle with a radius of 15 cm. If the distance of the chord from the center is 9 cm, what is the length of the chord?
Important Questions from Circles, Chords and Tangents
In a circle, a ten cm long chord is at a distance of 12 cm from the centre of the circle. The length of the diameter of the circle (in cm) is:
Chord AB of a circle of radius 10 cm is at a distance 8 cm from the centre O. If tangents drawn at A and B intersect at P., then the length of the tangent AP (in cm) is:
A chord 21 cm long is drawn in a circle of diameter 25 cm. The perpendicular distance of the chord from the centre is:
In a circle with radius 5 cm, a chord is at a distance of 3 cm from the centre. The length of the chord is:
O is the centre of this circle. Tangent drawn from a point P, touches the circle at Q. If PQ = 24 cm and OQ = 10 cm, then what is the value of OP?
