Question

●●●●初三数学问题--→圆●●●●

Answer 1

作OF⊥AB,OG⊥CD,则四边形OFEG是长方形,OF^2+0G^2=OE^2=1

OF、OG分别平分弦AB和弦CD,

AB^2=(2AF)^2=4AF^2=4(OA^2-OF^2)

CD^2=(2CG)^2=4CG^2=4(OC^2-OG^2)

AB^2+CD^2

=4(OA^2-OF^2)+4(OC^2-OG^2)

=4OA^2+4OC^2-4(OF^2+OG^2)

=4*2^2+4*2^-4*1

=28