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from image,can you plz tell me what happened to the step just next to the form. 2sin^2(theta)=1-cos2(theta),

Hi Muhammad,

From the sum of angle formula;

cos(A+B) = cosAcosB - sinAsinB

Letting A = B = θ

cos(2θ) = cosēθ - sinēθ

But we also know the identity; cosēθ + sinēθ = 1

and so

cos(2θ) = (1 - sinēθ) - sinēθ

2sinēθ = 1 - cos(2θ)

Hope that was what you were looking for.

Regards

Calculus

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