10-3 Formulas
Doouble Formulas
Sin 2(alpha)= 2sin(alpha)cos(alpha)
Cos2(alpha)= cos^2(alpha)-sin^2(alpha) or 1-2sin^2(alpha) or 2cos^2(alpha)-1
tan2(alpha)= 2tan(alpha)/1-tan^2(alpha)
Half Formulas
sin alpha/2=+/- the square root of 1-cos(alpha)/2
cos alpha/2= +/- the square root of 1+ cos(alpha)/2
tan alpha/2 = +/- the square root of 1-cos(alpha)/1+cos(alpha) or sin(alpha)/1+cos(alpha) or
1-cos(alpha)/sin(alpha)
Ex. Simplify 2sin(90 degrees)cos(90 degrees)
1) Sin2(90 degrees)
2)sin 180 degrees
3= 180-180= sin(0)
4)=0
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