উচ্চ মাধ্যমিকের ত্রিকোণমিতির সূত্রাবলী।

2 sinA  cosB = sin(A+B)+sin(A-B)
2 cosA  sinB = sin(A+B)-sin(A-B)
2 cosA  cosB = cos(A+B)+cos(A-B)
2 sinA  sinB = cos(A-B)-cos(A+B)
sinC+sinD = 2sin*C+D/2 * cos*C-D/2
sinC-sinD = 2cos*C+D/2 * sin*C-D/2
cosC+cosD = 2cos*C+D/2 * cos*C-D/2
cosC-cosD = 2sin*C+D/2 * sin*D-C/2
sin2θ = 2sinθ cos θ
cos2θ = cos2θ-sin2 θ
2cos2 θ-1 = 1-2sin2 θ
2sin2 θ = 1-cos2 θ
2cos2 θ = 1+cos2 θ
tan2 θ = 1-cos2 θ/1+cos2 θ
sin2 θ = 2tanθ/1+tan2 θ
cos2 θ = 1-tan2 θ/1+tan2 θ
tan2 θ = 2tan θ/1-tan2 θ
tan3 θ = 3tan θ-tan3 θ/1-3tan2 θ
sin3 θ = 3sinθ-4sin3θ
cos3θ = 4cos3θ-3cosθ
sinθ = 2sin* θ/2 * cos* θ/2
cosθ = cos2 * θ/2 – sin2 * θ/2
2cos2 * θ/2*-1 = 1-2sin2 θ/2
2sin2 * θ/2 = 1-cos θ
2cos2 * θ/2 = 1+cos θ
tan2* θ/2 = 1-cosθ/1+cosθ
sinθ = 2tan* θ/2 /  1+tan2* θ/2
cosθ = 1-tan2* θ/2 /  1+tan2 θ/2
tanθ = 2tan* θ/2 /  1-tan2* θ/2
sinθ = 3sin* θ/3 – 4 sin3* θ/3
cosθ = 4cos3* θ/3 –  3cos* θ/3
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