Q 9( i )

Sin(3x)Sin(x) = Cos(x) Cos(3x)
Sin(3x)Sin(x) - Cos(x)Cos(3x) = 0 Apply the Trig Identity for Cos
Cos(3x + x) = 0
Cos(4x) = 0
4x = Cos^-1(0)
4x = pi
x = pi /4 = 22.5 degrees
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