初中_数学_初三【数学】_九下数学-试题_新人教版九年级下册数学全套试题_新人教版九年级数学下册第28章——28.2《解直角三角形及其应用》同步检测_新人教版九年级数学下册第28章——28.2《解直

人教版九年级数学下册第二*章《锐角三角函数——解直角三角形及其应用》同步检测2附*1.如图,由D点测塔顶A点和塔基B点仰角分别为60°和30°.已知塔基出地平面20米(即BC为20米)塔身AB的高为[][来源:学科网ZXXK]INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30147.jpg"\*MERGEFORMATIINCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30148.jpg"\*MERGEFORMATI2.如图,一敌机从一高*正上方2000米经过,沿水平方向飞行,稍后到达B点,这时仰角为45°,1分钟后,飞机到达A点,仰角30°,则飞机从B到A的速度是[]米/分.(精确到米)A.1461B.1462C.1463D.1464INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30149.jpg"\*MERGEFORMATI3.如图所示,河对岸有水塔CD.今在A处测得塔顶C的仰角为30°,前进20米到达B处,又测得C的仰角为45°,则塔高CD(精确到0.1m)是[]m[来源:学。科。网]A.25.3B.26.3C.27.3D.28.3INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30150.jpg"\*MERGEFORMATI4.如图：在200米高的峭壁上,测得一塔的塔顶与塔基的俯角分别为30和60°,那么塔高是[]米INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30151.jpg"\*MERGEFORMATIINCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30152.jpg"\*MERGEFORMATI来源：.bcjy123./tiku/5.如图：从B处测得建筑物上旗杆EC顶点C的仰角是60°,再从B的正上方40米高层上A处,测得C的仰角是45°,那么旗杆顶点C离地CD的高度是[]米.INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30153.jpg"\*MERGEFORMATIINCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30154.jpg"\*MERGEFORMATI二、填空题1.如图：已知在一峭壁顶点B测得地面上一点A俯角60°,竖直下降10米至D,测得A点俯角45°,那么峭壁的高是_____________米(精确到0.1米)INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30158.jpg"\*MERGEFORMATI三、解答题1.从山顶D测得同一方向的A、B两点，俯角分别为30°,60°,已知AB=140米,求山高(A、B与山底在同一水平面上).(*可带根号)2.从与塔底在同一水平线的测量仪上,测得塔顶的仰角为45°,向塔前进10米,(两次测量在塔的同侧)又测得塔顶的仰角为60°,测量仪高是1.5米,求塔高(精确到0.1米).[来源:学科网]3.两山脚B、C相距1500米,在距山脚B500米处A点,测得山BD、CE的山顶D、E仰角分别为45°,30°.求两山的高(精确到1米).INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30159.jpg"\*MERGEFORMATI4.如图：山顶上有高为h的塔BC,从塔顶B测得地面上一点A的俯角是a,从塔底C测得A的俯角为b,求山高H.INCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30160.jpg"\*MERGEFORMATI[来源:Z&xx&k.]参考*一、选择题1.C2.D3.C4.B5.C二、填空题23.7三、解答题1．false米2.25.2米3.500米,577米4.解：∵DA=(h+H)ctga,DA=Hctgb[来源:Zxxk.]则Hctgb=hctga+Hctga来源：.bcjy123./tiku/即H(ctgbctga)=hctgaINCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30156.jpg"\*MERGEFORMATIINCLUDEPICTURE"star.5ewy.:8080/RESOURCE/CZ/CZSX/DGJC2/JH3/JZJSJX/JZJSJX/lxj30157.jpg"\*MERGEFORMATI来源：.bcjy123./tiku/来源：.bcjy123./tiku/