Step 1: Construct a imaginary figure according to given hints

EXAMPLE: Let PQ be a chord of a circle with centre O and radius 13cm

such that PQ = 24cm.

Step 2: Draw (OM) perpendicular line to the chord (PQ) and join the center and the end point of the chord.

Step 3: Find the base of the right angle triangle

NOTE: The perpendicular from the centre of a circle to a chord bisects the chord.

EXAMPLE ∴ Base PM = 12cm

Step 4: Recall the Pythagoras theorem to calculate the unknown value

NOTE: (Hypotenuse)^2 = (height)^2 + (Base)^2

Step 5: Substitute all the known values in the Pythagoras formula and simplify the equation.

EXAMPLE: In △OMP, we have

OP^{2 }= OM^{2} + PM^{2}

⇒ 13^{2 }= OM^{2 }+ 12^{2}

⇒ OM = 5cm.

Hence, the distance of the chord from the centre is 5cm.