cos+π+α+等于多少

人汤馨3955cos(a - π)等于多少 -
冷荷果18469913518 ______ cos(-π-a)=cos(π+a)=-cosa 朋友,请及时采纳正确答案,下次还可能帮您,您采纳正确答案,您也可以得到财富值,谢谢.

人汤馨3955式子cos^2(π/4 - α)+cos^2(π/4+α)=?_
冷荷果18469913518 ______ cos^2(π/4-α)+cos^2(π/4+α)=sin^2[π/2-(π/4-α)]+cos^2(π/4+α)=sin^2(π/4+α)+cos^2(π/4+α)=1

人汤馨3955请问COS(π/3+α)等于多少? -
冷荷果18469913518 ______[答案] 对不起!才看见 用和角公式展开 cos(π/3+a)=cosπ/3cosa-sinπ/3sina=(1/2)cosa-(√ 3/2)sina

人汤馨3955cos(π+α)= - 1/2,3π/2<α<2π,则sin(α+3π)等于多少? -
冷荷果18469913518 ______[答案] 3π/2<α<2π 5π/2<α+π<3π 周期为2π π/2<α+π<π,α+π在第二象限,cos为负,sin为正 cos(π+α)=-1/2 sin(α+3π)=sin(α+3π-2π)=sin(α+π)=√3/2

人汤馨3955若sin((π/6) - α)=1/3,则cos((2π/3)+2α)等于多少? -
冷荷果18469913518 ______ sin((π/6)-α)=1/3,而sin((π/6)-α)=cos[π/2-((π/6)-α))]= cos((π/3)+α),∴cos((π/3)+α)=1/3.所以cos((2π/3)+2α)= cos[2((π/3)+α)]= 2cos²((π/3)+α)-1=-7/9.

人汤馨3955cos(2π+α)=? -
冷荷果18469913518 ______ coa(2π+α)=coaα 以为一个角加上2π相当于还是原来那个角 如果还有什么不明白的地方欢迎再问哦亲~

人汤馨3955【急】推导诱导公式 cos(π/2+α)= - sinα tan(π/2+α)=-cotα cot(π/2+α)=-tan-
冷荷果18469913518 ______ cos(π/2+α)=-sinα ,tan(π/2+α)=-cotα, cot(π/2+α)=-tan诱导公式.推导过...

人汤馨3955已知sin(π+α)= - 1/2则cos(α+π/2)等于多少?sin(α+π/2)等于多少? sin(5π - α)等于多少 ? -
冷荷果18469913518 ______ sin(π+α)==-sina=-1/2 sina=1/2所以cosa=√3/2或-√3/2 cos(α+π/2)=-sina=-1/2 sin(α+π/2)=cosa=√3/2或-√3/2 sin(5π-α)=sina=1/2 tan(π/2-α)=cota=cosa/sina=√3或-√3

人汤馨3955已知cos(0.25π+α)=0.6,αε0.5π,1.5π - ?
冷荷果18469913518 ______ pi/23pi/40--->sin(a+pi/4)=-4/5 --->cos2(a+pi/4)=2[cos(a+pi/4)]^2-1=2(3/5)^2-1=-7/25 ……sin2(a+pi/4)=2sin(a+pi/4)cos(a+pi/4)=2(3/5)(-4/5)=-24/25 cos(2a+pi/4) =cos[2(a+pi/4)-pi/4] =cos2(a+pi/4)cos(pi/4)+sin2(a+pi/4)sin(pi/4) =(-7/25)(√2/2)+(-24/25)(√2/2) =-31√2/50.

人汤馨3955已知cos(π+α)=1/2,计算sin(2π - α) sin[(2n+1)π+α]+sin[α - (2n+1)π]/sin(2nπ+α)cos(α - 2nπ) -
冷荷果18469913518 ______[答案] cos(π+α)=1/2 ∴cosa=-1/2 ∴sina=±√3/2 ∴原式 =[(-sina)(-sina)+(-sina)]/(sinacosa) =(sina-1)/cosa =2±√3