Question

If a chord of length 8 cm is at a distance of 3 cm from the centre of circle what is the radius of circle

Answer 1

The chord is 8cm. A perpendicular drawn from center of circle on this chord is 3cm. This perpendicular bisects the chord into 4cm, 4cm. Now we can imagine a right-angled triangle with base 4cm, height 3cm and hypotenues joining the center with the end of chord. Now using pythagorous theorem, 
3² + 4² = r² (r is radius) 
√25= r
∴ r = 5cm.
Radius is 5cm.