BD is the angular bisector of △ ABC, de ⊥ BC and E. if s △ ABC = 60cm to the second power; ab = 12cm, BC = 18cm, then s △ DBC = - CM & # 178;, de = - cm

∵ BD bisection ∠ ABC
∴AD/CD＝AB/BC
∵AB＝12,BC＝18
∴AD/CD＝12/18＝2/3
∵S△ABC＝60
∴S△DBC＝S△ABC×3/（2+3）＝60×3/5＝36（cm²）
∵DE⊥BC
∴S△DBC＝BC×DE/2＝18×DE/2＝9DE
∴9DE＝36
∴DE＝4（cm）

BD is the angular bisector of △ ABC, de ⊥ BC and E. if s △ ABC = 60cm to the second power; ab = 12cm, BC = 18cm, then s △ DBC = - CM & # 178;, de = - cm

BD is the angular bisector of △ ABC, de ⊥ BC and E. if s △ ABC = 60cm to the second power; ab = 12cm, BC = 18cm, then s △ DBC = - CM & # 178;, de = - cm

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