The angles subtended by a chord at the center of a circle of radius 13 cm is 48°. How far is the chord to the center of the circle

1 answer

Let O be the center of the circle, and let AB be the chord subtending an angle of 48° at the center.

Since the angle subtended by the chord at the center is 48°, we know that the angle subtended by the same chord at the circumference is half of that, which is 24°.

We can draw a perpendicular from the center of the circle to the chord, which will bisect the chord and subtend a right angle at the point of intersection.

Let M be the midpoint of the chord AB, and let OM be the perpendicular from the center O to the midpoint M.

Since OM is perpendicular to the chord AB, we have formed two right-angled triangles OMA and OMB. Since OM bisects the chord, both triangles are congruent by the Side-Angle-Side (SAS) criterion.

Therefore, the length of the chord AB is 2 * AM.

In triangle OMA,

AM = OA * sin(24°) = 13 * sin(24°)

Using a calculator, we find that sin(24°) ≈ 0.4067.

Thus, AM = 13 * 0.4067 ≈ 5.2821 cm.

Therefore, the distance from the chord to the center of the circle is half the length of the chord, which is:

AB = 2 * AM = 2 * 5.2821 ≈ 10.5642 cm.

Therefore, the distance from the chord to the center of the circle is approximately 10.56 cm.