Answer:
3 cm
Step-by-step explanation:
A line from the centre of the circle at right angles to the chord is a perpendicular bisector.
Thus a right triangle is formed with legs d , the line from centre to chord and 4 , half the length of the chord. The radius 5 is the hypotenuse.
Using Pythagoras' identity in the right triangle.
4² + d² = 5², that is
16 + d² = 25 ( subtract 16 from both sides )
d² = 9 ( take the square root of both sides )
d = [tex]\sqrt{9}[/tex] = 3
Thus the chord is 3 cm from the centre of the circle.
OB = 3 cm
AO = radius = 5 cm
AB = 8cm/2 = 4 cm
Pythagora
OB² = AO² - AB²
= (5cm)² - (4cm)²
= 25cm² - 16cm²
= 9 cm²
OB = √9cm²
= 3 cm
