Trigonometry Formulas

• sin²x + cos²x = 1
• tan²x + sec²x = 1
• cosec²x + cot²x = 1
• sin2x = 2sinxcosx
• sinx = 2sinx|2cosx|2
• cos2x = 2cos²x-1
• cos2x = 1-2sin²x
• cos2x = 1 - tan²x/1 + tan²x
• cos2x = cos²x - sin²x
• sin2x = 2tanx/1 + tan²x
• 1 - cosx = 2cos²x/2
• 1 + cosx = 2sin²x/2
• tan2x = 2tanx/1-tan²x
• sin3x = 3sinx - 4sin³x
• cos3x = 4cos³x - 3cosx
• tan3x = 3tanx - tan³x/1 - 3tan²x
• sin(x+y) = sinxcosy + cosxsiny
• sin(x-y) = sinxcosy - cosxsiny
• cos(x+y) = cosxcosy - sinxsiny
• cos(x-y) = cosxcosy + sinxsiny
• tan(x+y) = tanx + tany/1 - tanxtany
• tan(x-y) = tanx - tany/1 + tanxtany
• cot(x+y) = cotxcoty - 1/cotx + coty
• cot(x-y) = cotxcoty + 1/coty - cotx
• sin(x+y) * sin(x-y) = sin2x - sin2y or cos2y - cos2x
• cos(x+y) * cos(x-y) = cos2x - sin2y or cos2y - sin2x
• sin(x+y) + sin(x-y) = 2sinxcosy
• sin(x+y) - sin(x-y) = 2cosxsiny
• cos(x+y) + cos(x-y) = 2cosxcosy
• cos(x-y) - cos(x+y) = 2sinxsiny
• 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