铃木cos雷电将军
@穆倪1706：化tan( - 330°)tan420°cos390°cos1140°sin750° -
蔡鬼17739659073…… 解:tan(-330°)tan420°cos390°cos1140°sin750°=tan(30°)tan(60°)cos(30°)cos(60°)sin(30°)=cos(30°)cos(60°)sin(30°)=sin(60°)cos(60°)sin(30°)=0.5sin(120°)sin(30°)=0.5sin(60°)x0.5=0.25x√(3)÷2=0.25x0.5x√3=0.125√(3)=8分之√(3)
@穆倪1706：sinx=cos0.5x - 作业帮
蔡鬼17739659073…… [答案] sinx=2sin1/2x1/2cosx=cos0.5x 故sino.5x=1/2 0.5x=30° x=60°
@穆倪1706：COS420度的值为 - 作业帮
蔡鬼17739659073…… [答案] cos420° =cos(60°+360°) =cos60° =1/2
@穆倪1706：为什么 - cos110°等于sin20° - 作业帮
蔡鬼17739659073…… [答案] -cos110º=-cos(90º+20º)=-(-sin20º)=sin20º 诱导公式:cos(90º+a)=-sina
@穆倪1706：已知tanα=2,求sinα和cosα. - 作业帮
蔡鬼17739659073…… [答案] 由tanα=2>0,得到α在第一或第三象限,∵tanα=sinαcosα=2,∴sin2αcos2α=4,即sin2α1−sin2α=4,整理得:sin2α=45,当α在第一象限时,sinα=255,cosα=sinαtanα=55;当α在第三象限时,sinα=-255,co...
@穆倪1706：cos(10t) - cos(30t) 的周期T - 作业帮
蔡鬼17739659073…… [答案] f(t)=cos(10t)+cos(30t) =cos(10t)+cos(10t)cos(20t)-sin(10t)sin(20t) =cos(10t)+cos(10t)*[2cos(10t)^2-1]-2cos(10t)*sin(10t)^2 ... =2cos(10t)*[2cos(10t)^2-1] =4cos(10t)^3-2cos(10t) 因为y=cos(t)的周期为2π 所以y=cos(10t)的周期为2π/10=π/5 f(t)=4cos(10t)^3-2...
@穆倪1706：已知tanα=2/3,则cos2α=? - 作业帮
蔡鬼17739659073…… [答案] cos2a =cos²a-sin²a =(cos²a-sin²a)/(cos²a+sin²a) =(1-tan²a)/(1+tan²a) =(1-4/9)/(1+4/9) =5/13
@穆倪1706：Cos30° 45° 60°是多少? - 作业帮
蔡鬼17739659073…… [答案] COS30=√3/2. cos45=√2/2. cos60=1/2. tan30=√3/3. tan45=1. tan60=√3.
@穆倪1706：cosπ/9cos2π/9cos23π/9 -
蔡鬼17739659073…… cosπ/9cos2π/9cos23π/9 =[2sinπ/9cosπ/9cos2π/9cos23π/9]/2sinπ/9 =[sin2π/9cos2π/9cos(2π+5π/9)]/2sinπ/9 =[sin4π/9cos5π/9]/4sinπ/9 =-[sin4π/9cos4π/9]/4sinπ/9 =-(sin8π/9)/8sinπ/9 =-(sinπ/9)/8sinπ/9 =-1/8
@穆倪1706：cos7π/6=? - 作业帮
蔡鬼17739659073…… [答案] cos7π/6=cos(π+π/6) =-cos(π/6) =-cos30° =-sin60° =-(√3)/2 亲,请您点击“采纳答案”,您的采纳是我的动力,谢谢.
蔡鬼17739659073…… 解:tan(-330°)tan420°cos390°cos1140°sin750°=tan(30°)tan(60°)cos(30°)cos(60°)sin(30°)=cos(30°)cos(60°)sin(30°)=sin(60°)cos(60°)sin(30°)=0.5sin(120°)sin(30°)=0.5sin(60°)x0.5=0.25x√(3)÷2=0.25x0.5x√3=0.125√(3)=8分之√(3)
@穆倪1706：sinx=cos0.5x - 作业帮
蔡鬼17739659073…… [答案] sinx=2sin1/2x1/2cosx=cos0.5x 故sino.5x=1/2 0.5x=30° x=60°
@穆倪1706：COS420度的值为 - 作业帮
蔡鬼17739659073…… [答案] cos420° =cos(60°+360°) =cos60° =1/2
@穆倪1706：为什么 - cos110°等于sin20° - 作业帮
蔡鬼17739659073…… [答案] -cos110º=-cos(90º+20º)=-(-sin20º)=sin20º 诱导公式:cos(90º+a)=-sina
@穆倪1706：已知tanα=2,求sinα和cosα. - 作业帮
蔡鬼17739659073…… [答案] 由tanα=2>0,得到α在第一或第三象限,∵tanα=sinαcosα=2,∴sin2αcos2α=4,即sin2α1−sin2α=4,整理得:sin2α=45,当α在第一象限时,sinα=255,cosα=sinαtanα=55;当α在第三象限时,sinα=-255,co...
@穆倪1706：cos(10t) - cos(30t) 的周期T - 作业帮
蔡鬼17739659073…… [答案] f(t)=cos(10t)+cos(30t) =cos(10t)+cos(10t)cos(20t)-sin(10t)sin(20t) =cos(10t)+cos(10t)*[2cos(10t)^2-1]-2cos(10t)*sin(10t)^2 ... =2cos(10t)*[2cos(10t)^2-1] =4cos(10t)^3-2cos(10t) 因为y=cos(t)的周期为2π 所以y=cos(10t)的周期为2π/10=π/5 f(t)=4cos(10t)^3-2...
@穆倪1706：已知tanα=2/3,则cos2α=? - 作业帮
蔡鬼17739659073…… [答案] cos2a =cos²a-sin²a =(cos²a-sin²a)/(cos²a+sin²a) =(1-tan²a)/(1+tan²a) =(1-4/9)/(1+4/9) =5/13
@穆倪1706：Cos30° 45° 60°是多少? - 作业帮
蔡鬼17739659073…… [答案] COS30=√3/2. cos45=√2/2. cos60=1/2. tan30=√3/3. tan45=1. tan60=√3.
@穆倪1706：cosπ/9cos2π/9cos23π/9 -
蔡鬼17739659073…… cosπ/9cos2π/9cos23π/9 =[2sinπ/9cosπ/9cos2π/9cos23π/9]/2sinπ/9 =[sin2π/9cos2π/9cos(2π+5π/9)]/2sinπ/9 =[sin4π/9cos5π/9]/4sinπ/9 =-[sin4π/9cos4π/9]/4sinπ/9 =-(sin8π/9)/8sinπ/9 =-(sinπ/9)/8sinπ/9 =-1/8
@穆倪1706：cos7π/6=? - 作业帮
蔡鬼17739659073…… [答案] cos7π/6=cos(π+π/6) =-cos(π/6) =-cos30° =-sin60° =-(√3)/2 亲,请您点击“采纳答案”,您的采纳是我的动力,谢谢.
