Question

在矩形abcd中,点e在ad上,ec平分角BED若ab=1角abe=45度求AD长

Answer 1

∠BED = ∠BAE+∠ABE = 90°+45° = 135° ,∠DCE = 90°-∠CED = 90°-(1/2)∠BED = 22.5° ,tan22.5° = tan(45°/2) = (1-cos45°)/sin45° = √2-1 ,CD = AB = 1 ,AE = AB*tan∠ABE = AB*tan45° = 1 ,DE = CD*t...