B
bobobo123ken


1.sin2x + 2cos2x = 1 + sinx - 4cosx
2.$sin^4\frac{x}{2}$+$cos^4\frac{x}{2}$=1 - 2sinx
3.cos3x $cos^{3}x$- sin3x$sin^{3}x$= $cos^{3}4x$ + $\frac{1}{4}$
2.$sin^4\frac{x}{2}$+$cos^4\frac{x}{2}$=1 - 2sinx
3.cos3x $cos^{3}x$- sin3x$sin^{3}x$= $cos^{3}4x$ + $\frac{1}{4}$
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