【導(dǎo)讀】4.如圖,△ABC中,∠ABC=150°,CD是角平分線,BC=a,AC=b,AB=c,6.如圖,在△ABC中,AB=AC,AD是BC邊上的高.若△ABC的面積為9cm2,A2,使得A1A2=A1C,在A2C上取一點(diǎn)D,延長A1A2到A3,使得A2A3=A2D,……12.在Rt△ABC中,∠ACB=90°,∠CAB=36°,在直線AC或BC上取點(diǎn)M,平地上修建一個度假村.要使這個度假村到三條公路的距離相等,則度假村應(yīng)該修在何處?15.分解因式:-x2+4xy-4y2=____________;和C、D兩點(diǎn),用直尺和圓規(guī)在AOB?如圖1,若∠ACD=60°,則∠AFD=__________;ABD=80°,求∠EAB的度數(shù);