PQ and RS are two chords of a circle with centre O. The perpendiculars drawn from O to PQ and RS are OX and OY respectively. Show that PQ² - RS² = 4OY - 4OX.

Answer:
Step-by-step explanation:
Radii PO and RO will be called r
Pythagorean theorem
r² = PX² + OX²
r² = RY² + OY²
PX² + OX² = RY² + OY²
PX² - RY² = OY² - OX²
similar triangles based on diameters rather than radii
(2PX)² - (2RY)² = (2OY)² - (2OX)²
PQ² - RS² = 4OY² - 4OX²
Going by the picture provided rather than your posted question which is missing a couple of squaring exponents on the right hand terms.