sin 2x = 2 sinx .cosx
cos 2x = cos2x - sin2x = 1 - 2 sin2x = 2 cos2x - 1
2 .cos A. cos B = cos(A + B) + cos(A - B)
2 .sin A .sin B = -cos(A + B) + cos(A -B)
2 .sin A. cos B = sin(A + B) + sin(A -B)
2 .cos A .sin B = sin(A + B) - sin (A -B)
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sin 2x = 2 sinx .cosx cos 2x = cos2x - sin2x = 1 - 2 sin2x = 2 cos2x - 1 |
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2 .cos A. cos B = cos(A + B) + cos(A - B) 2 .sin A .sin B = -cos(A + B) + cos(A -B) 2 .sin A. cos B = sin(A + B) + sin(A -B) 2 .cos A .sin B = sin(A + B) - sin (A -B) |