Trigonometrie
Formule trigonometrice:
Sin = cateta opusa / ipotenuza
- Sin(-x)= - sinx
- Cos(-x)= cosx
- Tg(-x)= - tgx
- Ctg(-x)= - ctgx
- Sin(2π+x)=sinx
- Cos(2π+x)=cosx
- Tg(π+x)=tgx
- Ctg(π+x)=ctgx
- Sin(π±x)= - + sinx
- Cos(3π/2±x)= ±sinx
- Tg(π/2+x)= - ctgx
- Ctg(-π/2+x)= - tgx
- Ctg(3π-x)= - ctgx
- Tg(5π/2+x)= - ctgx
- Sec x=1/cosx
- Sin(x+y)=sinxcosy + sinycosx
- Cos(x+y)=cosxcosy - sinxsiny
- Tg(x+y)=(tgx + tgy)/(1 – tgx* tgy)
- Sinx+siny=2sin[(x+y)/2] *cos[(x-y)/2] -suma in produs
- Cosx+cosy=2cos[(x-y)/2]*cos[(x+y)/2] -suma in produs
- Cosx-cosy=2sin[(x-y)/2]*sin[(x+y)/2] -suma in produs
- Sin(2x)=2sinxcosx -omogenizarea (1/2x)
- Cos(2x)=cos2x-sin2x -omogenizarea (1/2x)
- 2sinxcosy=sin(x-y)+sin(x+y) -produs in suma
- 2cosxcosy=cos(x-y)+cos(x+y) -produs in suma
- 2sinxsiny=cos(x-y)-cos(x+y) -produs in suma
- Tg(2x)=2tgx/(1-tg2x)
- 1+cos(2x)=2cos2x
- 1-cos(2x)=2sin2x
- 1+tg2x=1/cos2x
- 1+ctg2x=1/ sin2x
Radiani Grade Sin Cos Tg Ctg 360 g = 2 π rad
0 0 0 1 0 NA 1 rad = 57,32 g
π/6 30 1/2 √3/2 1/√3 √3
π/4 45 √2/2 √2/2 1 1 Grade in radiani: g*π/180
π/3 60 √3/2 1/2 √3 1/√3 Radiani in grade: 180*rad/π
π/2 90 1 0 NA 0
π 180 0 -1 0 NA Ecuatii:
3π/2 270 -1 0 NA 0
2π 360 0 1 0 NA sinx = a, |a|<1, nu are solutii
|a|≤1, x = (-1)n arcsin a+nπ
cosx = a, |a|<1, nu are solutii
|a|≤1, x = ±arccos a+2kπ
tgx = a, x = arctg a+nπ
ctgx = a, x = arccgt a+nπ