第 1 节 三角函数的相关概念
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第 1 节 三角函数的相关概念. 第四章 三角函数. 要点 · 疑点 · 考点. 1. 角的概念的推广 所有与 α 角终边相同的角的集合 S={ β | β = α + k ·360° , k ∈Z}. 2. 弧度制 任一个已知角 α 的弧度数的绝对值 |α| = l / r ( l 是弧长, r 是半径 ) , 1° = π/180 弧度, 1rad=(180/π)°≈57.30° = 57°18′ 弧长公式 l =| α | r ,扇形面积公式 S = 1/2 lr. 3. 任意角三角函数的定义 - PowerPoint PPT PresentationTRANSCRIPT
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3. P(xy)Prsin=y/rcos=x/r tan=y/xcot=x/ysec=r/xcsc=r/y. 1. S={|+k360kZ} 2. ||l/r ( lr)1/1801rad=(180/)57.305718 l=||rS1/2lr
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4.sincsc1cossec1 tancot1tan=sincoscotcossin sin2+cos211+tan2=sec21+cot2=csc2 5.sincsccossectancot,
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1.[02)PP(sin-costan).q:[/2].Pq( )(A) (B)(C) (D) A2.P(-5-12)cos= _______ tan =_______. -5/1312/5A
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5.(02)sincos0sincos0( ) (A)(/23/4)(B)(3/4) (C)(/23/4)(7/42)(D)(3/4)(3/7/4) 4.2x( ) (A) (B) (C) (D) CC
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. 1./2?2?
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2sin=m (|m|1) tan. .(1).(2).(3)...
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x23Px
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5.R. 60R10cm. C(C0)?? ..
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1.. 2..
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2
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1. +k360(kZ)-180360-. n90(nZ)
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1.x(-/20)cosx=4/5tan2x=( ) (A)7/24 (B)-7/24 (C)24/7 (D)-24/7 DAC
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CB
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1.cos(-)= -4/5cos(+)=12/13-( /2)+(3/22)cos2cos2. 2+-(+)+(-)=2,(+)-(-)=2()
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tansincos. 4.tan(-)=12,tan =-17,(0).2-. . (1)(2) (3).
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1.2.3.1.
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3
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1. MPOMAT.
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2. (1)y=sinxy=cosxy=tanxy=cotx() (2)y=Asin(x+) (3) y=sinxy=Asinx y=sinxA() y=Asinxy=Asin(x+) y=Asinx(0)(0)|| y=Asin(x+)y=Asin(x+)y=Asin(x+) 1/ ().
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3. y=Asin(x+)(A00). (1)y=Asin(x+)x=xk(xk+=k+/2kZ). (2)y=Asin(x+)(xj ,0)(xj+=k,kZ).
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1.:(A)y=cos(2x+/6) (B)y=sin(2x+/6)(C)y=sin(x/2+/6) (D)y=tan(x+/6) ( ) (/60). 2.f(x)=sin(x+/2)g(x)=cos(x-/2)( ) (A)y=f(x)g(x)2 (B)y=f(x)g(x)1 (C)f(x)/2g(x) (D)f(x)/2g(x) AD
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3.y=f(x)sinx/4xy=1-2sin2xf(x)( ) (A)cosx (B)2cosx (C)sinx (D)2sinx
B4.y=|tgx|cosx(0x3/2x/2)( C )
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5.f(x)=sin(3x-3/42/3y=2sin3x/4y=2cos(3x-/4)x[/125/12]._________
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1.y=f(x)/8y=3sin(x+/6).f(x)y=Asin(x+)
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2.y=sin2x+acos2xx=-/6a.
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A00y=Asin(x+)y=sinx(0)(0)||(1)(01)1/()(A1)(0A1)A()y=Acos(x+)y=Atan(x+)y=cosxy=tanx.
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x=x+/6y=yy=3sin2xx=x-/6y=3sin[2(x-/6)]4.y=Asin(x+)(A00)(5/123)(11/12-3)
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5.f(x)=sin(x+)(00)RM(3/40)[0/2].. 1.42.y=sinxy=sin(2x+/3)1/2y=sin2x/6/3.
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1. (1)y=sinx[2k-/22k+/2](kZ)[2k+/22k+3/2](kZ) (2)y=cosx[2k+2k+2](kZ)[2k2k+](kZ) (3)y=tanx(k-/2k+/2)(kZ) 2. y=sinx,y=cosx,y=tanx.
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3. (1) y=f(x)Txf(x+T)=f(x)y=f(x)T (2)
(3)ysinx,y=cosxT=2 y=tanx,y=cotxT=
(4) y=Asin(x+)+kT=2/(0) y=Atan(x+)+kT=/(0)
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1.(0,/2)( ) (A)y=sin(x/2) (B)y=sin2x (C)y=-tanx (D)y=-cos2x 2.f(x)=Asin(x+)(A00)2( ) (A)f(x+2) (B)f(x+2) (C)f(x-2) (D)f(x-2) 3.f(x)=asin(x+)+bcos(x+)+4f(2001)=5f(2002)=( ) (A)1 (B)3 (C)5 (D)7 DAB
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4.y=2sin2x+sin2x( ) (A)2 (B)2 (C) (D)
5.( ) (A)sinsin (B)y=sinxcotx(2k-/22k+/2)kZ (C)y=(1-cos2x)/sin2x2 (D)y=sinxcos2-cosxsin2y =k/2+/4kZ DD
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f(-x)=-f(x)f(-x)=f(x)..
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y=f(x)Tf(x+)T||
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y=f(x)y=Asin(x+)().
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4.f(x)=log(1/2)(sinx-cosx) (1) (2) (3) (4)
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xRf(x)? 5.f(x)(-+)f(x+2)=-f(x)xRx[-11]f(x)=x3 x[15]f(x) f(-5)
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1.2.y=2sin(/3-2x)x3.y=Asin(x+)2/
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1. y=sinxR[-1,1]x=2k-/2(kZ)-1x=2k+/2(kZ)1 . 2. y=cosxR[-11]x=2k(kZ)1x=2k+(kZ)-1 3. y=tanx(k-/2k+/2)(kZ)R.
- 2k+/6x2k+5/6kZ2k+5/6
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BB
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y=acos2x+bcosxsinx+csin2x+d(abcd)y=Acos(2x+)+B
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2.y=sinx+cosx+2sinxcosx+2.x[0/2]? sinx+cosxsinxcosx.()sinx+cosx,sinx-cosxsinxcosxt..
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4.f(x)=-sin2x-asinx+b+10-4a0a,by=asin2x+bsinx+c.y=at2+bt+c[-11].
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5.RtABCBC(1)AB=a,ABC=ABCPQ(2)P/Q
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2.2.
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1. (1)a/sinA=b/sinB=c/sinC=2R(RABC). (2)S=absinC/2=bcsinA/2=casinB/2 2. a2=b2+c2-2bccosA b2=c2+a2-2cacosB c2=a2+b2-2abcosC 3.() (1)tanA+tanB+tanC=tanAtanBtanC(2)sinA+sinB+sinC=4cos(A/2)cos(B/2)cos(C/2) (3)cosA+cosB+cosC=4sin(A/2)sin(B/2)sin(C/2)+1 (4)sin2A+sin2B+sin2C=4sinAsinBsinC (5)cos2A+cos2B+cos2C=-4cosAcosBcosC-1
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CB
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AD
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...
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(2).
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..4.ABCtanA=1/2,tanB=1/31. (1)C(2).
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ABCABC()()()()..
abc
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2..1..