Traditional Culture Encyclopedia - Weather forecast - (20 12? As shown in the figure, in △ABC, AD is the center line of BC, BC=4, ∠ ADC = 30, and △ADC folds back to point C along the straight line where AD is located.

(20 12? As shown in the figure, in △ABC, AD is the center line of BC, BC=4, ∠ ADC = 30, and △ADC folds back to point C along the straight line where AD is located.

Answer: DE⊥BC' in E.

According to the nature of folding, CD = c'd, ∠ADC'=∠ADC = 30.

∵AD is the center line of triangle ABC,

∴BD=CD=2,

∴bd=c′d=2.

DE⊥BC',

∴∠bde=∠c′de=60。

∴de= 12c′d= 1.