已知sin[a 4分之π]=3分之1-搜答案-大师作文网

设为最佳哦

sin(a+π)=-sina=-根号3/2cosa=1/2cos(a-2分之3π)=-cosa=-1/2

问题补充：是求tan(α-2β)的值这是公式sin（α－β）＝sinαtan(π-β)=1/2β=90sin(α/2)-cos(α/2)=5分之根号10公式忘

∵α∈(π,2分之3π)∴cosα

tan(a-7π)=tan(a-7π+8π)=tan(a+π)=tana=-3/4a∈(π/2,3π/2)tana=-3/4∴a∈(π/2,π)cos^2a=1/(1+tan^a)=16/25∴cos

解cos2β-cos2α=cos[(a+β)+(β-α)]-cos[(β+α)-(β-α)]=cos(a+β)cos(β-α)-sin(a+β)sin(β-α)-cos(a+β)cos(β-α)-si

a属于（2分之π,π）是第二象限所以cosa

sinA+cosB=1/3(sinA+cosB)^2=sinA^2+cosB^2+2sinAcosB=1/9sinB-cosA=1/2(sinB-cosA)^2=sinB^2+cosA^2-2sinB

解；f(x)=sinx+sinxcosπ/3+cosxsinπ/3=sinx+1/2sinx+√3/2cosx=3/2sinx+√3/2cosx=√3sin(x+π/6)当x+π/6=-π/2+2kπ

tanα=2/31/(sinαcosα)=2/(2sinαcosα)=2/sin(2α)=2/(2tanα/(1+(tanα)^2))=(1+(tanα)^2)/tanα=(1+(2/3)^2)/(2

sinθ+cosθ=√2/3sinθ=√2/3-cosθsin^2θ=2/9-2√2/3cosθ+cos^2θ1-cos^2θ=2/9-2√2/3cosθ+cos^2θ2cos^2θ-2√2/3cos

cos&=5分之4.tan&=4分之3.tan2&=7分之24.cos2&=25分之7

解a∈(π/2,π)∴cosa

f(a)=cos(-π-a)分之sin(π-a)cos(2π-a)tan(-a+2分之3π)＝(-cosa)分之sina×cosa×tan[(2分之π)-a]=－sina×cosa/sina=－cos

tan2分之α=2tana=2tana/2/(1-tan^2a/2)=-4/3⑴tan(α+4分之π)=(tana+1)/(1-tana)=(-1/3)/(7/3)=-1/7⑵（6sinα+cosα）

解sin（π5/2+a）=sin（2π+π/2+a）=sin（π/2+a）=cosa=1/5

解答；f(x)=sin(2x+3分之π)∴sin(2x+π/3)=-3/5∵x∈(0,π/2)∴2x+π/3∈(π/3,4π/3)∵sin(2x+π/3)

sin(π-a)cos(2π-a)sin(-a+1.5π)/(tan(-a-π)sin(-π-a）)=sin(a)cos(a)sin(-a-0.5π)/(tan(-a)sin(π-a-2π）)=(-1

1、定义域是Rx系数是1所以T=2π/1=2π2、五点法即sin里取0,π/2,π,3π/2,π则x-π/3=0,x=π/3,sin(x-π/3)=0x-π/3=π/2,x=5π/6,sin(x-π/

π/4＜α＜3π/4cosα=5/13sinα=根号(1-cos^2α)=12/130＜β＜π/4sinβ=5/13cosβ=根号(1-sin^2β)=12/13sin(α+β)=sinαcosβ+c