Question

正方形ABCD中,E为AD的中点,BM⊥CE于M,AB =6 cm,则BM等于(　　)

A.                            B.

C.3                              D.

Answer 1

思路分析:在正方形ABCD中,?

∵AB =6 cm,E为AD中点,?

∴由勾股定理得CE =3 cm.连结BE,容易知道S_△BEC = S_{正方形ABCD} =18 cm².?

在△BEC中,S_△BEC = EC·BM,?

∴BM = = (cm).

答案:B