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1. 1) "You are given that cos 30 degrees = (sqrt(3))/2 and cos 45 degrees =1 / (sqrt(2)) determine the exact value of cos 75 degrees"

2) "Solve the equation sin2θ−(cos^2)θ=0, giving values of θ in the interval 0°<θ<360°"

Many thanks!
2. 1. Cos (A+B) = CosACosB - SinASinB
Cos 75 = Cos(30+45)....

Carry on from here.
3. 2. Sin2A = 2SinACosA
Cos^2(A) = 1-Sin^2(A)
4. (Original post by haarithiop)
1. Cos (A+B) = CosACosB - SinASinB
Cos 75 = Cos(30+45)....

Carry on from here.
life saver thank you so much! i didn't think of it in terms of that
5. (Original post by HeadHoncho)
2. Sin2A = 2SinACosA
Cos^2(A) = 1-Sin^2(A)
Thank you so much!!

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