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The big question about circle in the mathematics test questions of junior middle school grade three
1, connecting AO, CO △AOE and △COE are symmetric about OE.

△ AOE△ COE in the circle, so AE=CE.

Because ∠AEB=∠DEC.

Two circumferential angles subtended by an arc BD ∠ bad = ∠ BCD.

So △ Abe △ CDE

So AB=CD

Step 2 connect AB and OB

Because de = 1

So be = 1

Angle bde = 45

Angle AOB = 90

So ab = 5 √ 2

Find AO=7 in Rt△AEB.

So AD=7+ 1=8.

Hope to adopt. . .