1/2-cos^2π/8
=1/2(1-2cos^2π/8)
=-1/2(2cos^2π/8-1)
=-1/2cosπ/4..余弦二倍角公式
=-1/2*√2/2
=-√2/4
猜你喜欢
- 11.把下面的百分数化成分数 80%= 150%= 50%= 25%= 0.8%= 12.5%= 108%= 36%= 2.6/()=几分之几=0.75=()%
- 2AutoCAD坐标系统 AtuoCAD的绝对直角坐标系统、相对直角坐标系统和绝对极坐标系统的区别
- 3求下列溶液由水电离产生的c(H+)的浓度. (1)0.01mol/L HCL; (2)0.01mol/L NaOH
- 4In the summer each words which said to you,is I to your affirmation Believe
- 5常建 《题破山寺后禅院》 全诗注音
- 6尽量合情合理!
- 7贾平凹泉
- 8There is going to have a trip to the Great Wall(找错)
- 9We had a great time last week in the park(保持原句)
- 10一沿x轴正方向的力作用在一质量为3kg的质点上,已知质点的运动学方程为x=3t-4t(平方)+t(3次方),这里x以m为单位.求(1)力在最初4秒内做的功.(2)在t=1s时,力的瞬时功率.