2cos^2(67°30′)=
来源:学生作业帮 编辑:百度作业网作业帮 分类:数学作业 时间:2024/07/13 19:15:49
2cos^2(67°30′)=
2cos^2(67°30′)=1+cos135°=1-√2/2
再问: 噢,谢谢你!可不可以再帮我看看这一题? sin^4(112°30′)-cos^4(112°30′) =
再答: sin^4(112°30′)-cos^4(112°30′) =[sin^2(112°30′)-cos^2(112°30′)][sin^2(112°30′)+cos^2(112°30′)] =sin^2(112°30′)-cos^2(112°30′) =-cos(112°30′*2) =-cos(225°) =cos(135°) =-√2/2
再问: 噢,谢谢你!可不可以再帮我看看这一题? sin^4(112°30′)-cos^4(112°30′) =
再答: sin^4(112°30′)-cos^4(112°30′) =[sin^2(112°30′)-cos^2(112°30′)][sin^2(112°30′)+cos^2(112°30′)] =sin^2(112°30′)-cos^2(112°30′) =-cos(112°30′*2) =-cos(225°) =cos(135°) =-√2/2
2cos^2(67°30′)=
2cos 30°-2sin 60°·cos 45°=?
已知cos(75°+α)=13,则cos(30°-2α)的值为 ___ .
求证cos(720°+α)(2/cosα+tanα)(1/cosα-2tanα)=2cosα-3tanα
求证:a^2(cos^2b-cos^2c)+b^2(cos^c-cos^2a)+c^2(cos^2a-cos^2b)=0
证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4
2(cos x)^2=1+cos 2x,
∫ (1+cos^2 x)/cos^2 x dx =
p=cos a/cos 2a怎么化简?
cos?=根号3/2
Cos x=-1/2
cos(-2/3)π=?