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△ABC中,∠A∶∠B∶∠C=1∶2∶3,则∠B等于
A.30°
B.60°
C.90°
D.120°
在△ABC中,若|sinA-|+(-cosB)2=0,∠A、∠B都是锐角,则∠C的度数是( )
A.70° B.90° C.105° D.120°
△ABC中,AB=AC,∠A为锐角,CD为AB边上的高,I为△ACD的内切圆圆心,则∠AIB的度数是【 】
A.120° B.125° C.135° D.150°
Rt△ABC中,∠C=,AC=30,BC=40,则三角形的周长为
A.100
B.110
C.120
D.130