Paper 2 · Circle theorems
In a semicircle of radius 17 cm, two chords are drawn parallel to the diameter, of lengths 30 cm and 16 cm. Calculate the perpendicular distance between them.
Model answer
7 cm
Also accepted: 7cm, 7
Explanation: Distance from centre to the 30 cm chord=√(17²-15²)=8 cm; to the 16 cm chord=√(17²-8²)=15 cm; difference=15-8=7 cm.
Derived from ZIMSEC Mathematics Paper 2, November 1999, Q3
