Draw a circle in which a chord of 6 cm length stands at a distance of 3 cm from the centre. (Hint: Is it a circumcircle of a suitable triangle?)
To draw the required circle, we first calculate its radius using the relation chord length = . Given chord length is 6 cm and perpendicular distance is 3 cm, we have . Solving this, , so , which gives and radius cm.
Following the hint, we construct the circle as the circumcircle of a suitable triangle. A right-angled isosceles triangle with legs of 6 cm each is suitable. First, draw with and AB = BC = 6 cm. Next, find the midpoint O of the hypotenuse AC. Since the midpoint of the hypotenuse is the circumcentre for a right triangle, O is the centre. Draw the circle with centre O and radius OA ( cm).
In this circle, AB is a chord of 6 cm. The perpendicular distance from the centre O to the chord AB is half the length of the other leg BC (as O is the midpoint of AC). Thus, the distance is cm, satisfying the given conditions.
Explanation
The student uses the formula for chord length provided in the context to find the radius. The hint suggests using a circumcircle of a suitable triangle. A right-angled isosceles triangle with legs equal to the chord length (6 cm) has its circumradius equal to half the hypotenuse, which is cm. The distance from the circumcentre (midpoint of hypotenuse) to either leg is exactly half the other leg, which is 3 cm. This elegantly satisfies the problem's conditions.
Solution Steps
Step 1: Calculate the radius using the formula , yielding cm.
Step 2: Draw a right-angled isosceles triangle ABC with and AB = BC = 6 cm.
Step 3: Find the midpoint O of the hypotenuse AC.
Step 4: Draw the circle with centre O and radius OA = cm. Chord AB is 6 cm and its distance from O is 3 cm.