20 1 1 detailed answers to 25 questions in the second model mathematics test paper of the senior high school entrance examination in Huangpu District.

25. solution: (1) is in △MBC, ∠MCB=, BC=2.

And ∵M is the midpoint of the AC side,

∴AM=MC= BC= 1, ————————————— (1min)

∴MB=, ————————————— (1min)

And CH⊥BM is in H, then ∠MHC=,

∴∠MCH=∠MBC, ——————————————————— (1min)

∴ Xin ∠ mch = ————————————— (1min)

(2) In △MHC, —————— (1)

∴AM2=MC2=, that is ———————————— (2 points)

And ? ≈AMH =∠BMA,

∴△AMH∽△BMA, —————————————————— (1min)

∴∠ ABM = ∠ CAH。 —————————— (1min)

(3), ———————— (5 points)