已知圆锥母线长6cm,底面直径为5cm,则圆锥侧面积为______cm2.
底面直径为5cm,则底面周长=5πcm,圆锥侧面积=12×5π×6=15πcm2.
Over the past decades, the population in this country because of the rising birth rate, immigration and the declining death rate.
A.has been increasing
B.have been increasing
C.had increased
D.have increased
国家平面控制网数据处理依据的基准面是()
A.大地水准面
B.水准面
C.任意投影面
D.参考椭球面