all formulas for trigonomentry
Answers
Sin (– θ) = – Sin θ
Cos (– θ) = Cos θ
Tan (– θ) =– Tan θ
Sec (– θ) = + Sec θ
Cot (– θ) = – Cot θ
We need to understand that trigonometric ratios would change for angles- 90o ± θ and 270o ± θ and they will remain same for 180o ± θ and 360o ± θ. Let’s see what happens when we add or subtract θ from 90o ± θ and 270o ± θ
Sec (90o + θ ) = Cos θ
Cot (90o – θ ) = Cos θ
Tan (90o + θ ) = – Cot θ
Tan (90o – θ ) = Cot θ
Sec (90o + θ ) = Cosec θ
Sec (90o + θ ) = Cosec θ
Sin (270o – θ ) = – Cos θ
Sin (270o – θ ) = – Cos theta
sin2 A+cos2 A=1
sec2A-tan2 A=1
cosec2A-cot2A=1
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Trigonometry Class 11 Formulas
sin(−θ)=−sinθ
cos(−θ)=cosθ
tan(−θ)=−tanθ
cosec(−θ)=−cosecθ
sec(−θ)=secθ
cot(−θ)=−cotθ
Product to Sum Formulas
sinx siny=12[cos(x–y)−cos(x+y)]
cosxcosy=12[cos(x–y)+cos(x+y)]
sinxcosy=12[sin(x+y)+sin(x−y)]
cosxsiny=12[sin(x+y)–sin(x−y)]
Sum to Product Formulas
sinx+siny=2sin(x+y2)cos(x−y2)
sinx−siny=2cos(x+y2)sin(x−y2)
cosx+cosy=2cos(x+y2)cos(x−y2)
cosx−cosy=–2sin(x+y2)sin(x−y2)
Basic Formulas
sin(A+B)=sinAcosB+cosAsinB
sin(A−B)=sinAcosB–cosAsinB
cos(A+B)=cosAcosB–sinAsinB
cos(A–B)=cosAcosB+sinAsinB
tan(A+B)=tanA+tanB1–tanAtanB
tan(A–B)=tanA–tanB1+tanAtanB
cos(A+B)cos(A–B)=cos2A–sin2B=cos2B–sin2A
sin(A+B)sin(A–B)=sin2A–sin2B=cos2B–cos2A
sin2A=2sinAcosA=2tanA1+tan2A
cos2A=cosA–sin2A=1–2sin2A=2cos2A–1=1−tan2A1+tan2A
tan2A=2tanA1–tan2A
sin3A=3sinA–4sin3A=4sin(60∘−A).sinA.sin(60∘+A)
cos3A=4cos3A–3cosA=4cos(60∘−A).cosA.cos(60∘+A)
tan3A=3tanA–tan3A1−3tan2A=tan(60∘−A).tanA.tan(60∘+A)
sinA+sinB=2sinA+B2cosA−B2
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