单选题
The figure above shows the dimensions ofa rectangular board that is to be cut into four identical pieces by making cuts at points A, B, and C, as indicated. If x=45, what is the length of AB? (1 foot=12 inches)
The figure above shows the dimensions ofa rectangular board that is to be cut into four identical pieces by making cuts at points A, B, and C, as indicated. If x=45, what is the length of AB? (1 foot=12 inches)
【正确答案】
C
【答案解析】[解析] 如图所示做辅助线，其中EF⊥AB。根据长方形的性质可知EF=AE=6英寸=0.5英尺，[*]=10英尺，BE=BC，所以有：
AC=AE+EB+BC=2BE+AE
=10英尺
→BE=BC=4.75英尺
→AB=AE+BE=4.75+0.5
=5.25英尺=5英尺3英寸
AC=AE+EB+BC=2BE+AE
=10英尺
→BE=BC=4.75英尺
→AB=AE+BE=4.75+0.5
=5.25英尺=5英尺3英寸