In โณABC, D, E and F are the mid-points of sides BC, CA and AB respectively. If BC = 14.4 cm, CA = 15.2 cm and AB = 12.4 cm, what is the perimeter (in cm) of โณDEF?
PQ and RS are two parallel chords of a circle of length 14 cm and 48 cm, respectively, and lie on the same side of the centre O. If the distance between the chords is 17 cm, what is the radius (in cm) of the circle?
The following sentence has been split into four segments. Identify the segment that contains a grammatical error.
She performed / the task / at the best / of her ability.