Chord and centre: r^2 = d^2 + (half chord)^2

CAT has tested this idea 5 times across 4 papers, from 2018 to 2025. Solve one, and the others are the same method with different numbers or wording, which is why repeated concepts are the most efficient thing to practise.

Question	What it asks	Answer
CAT 2018 Slot 1 · QA Q30	parallel chords 4 and 6, 1 cm apart; radius	A
CAT 2020 Slot 2 · QA Q21	chord of outer circle tangent to inner concentric circle	10
CAT 2018 Slot 2 · QA Q8	chords subtending 60° and 120° at centre	B
CAT 2025 Slot 1 · QA Q12	parallel chords either side of centre; area of PQRS	C
CAT 2020 Slot 2 · QA Q9	chord through two given points; distance from centre	C

Part of Geometry (65 questions since 2017).