Express cos 20 theta in terms of sin 5 theta Share with your friends Share 9 Manbar Singh answered this cos 20θ=cos 210θ=2 cos210θ - 1=2 cos 25θ2 - 1=21 - 2 sin25θ2 - 1=21 + 4 sin45θ - 4 sin25θ - 1=2 + 8 sin45θ - 8sin25θ - 1=8 sin45θ - 8 sin25θ + 1 30 View Full Answer
