Consider the unit circle with AB as a diameter and C as any point on the circle. Further, let BAC = 0; AC=x,BC=y as shown in the figure below. A L 20 e B Use the figure and prove that LACB = by Prove x² + y² = 4 c) Use the cosine rule in AAOC, to obtaion cose in terms of x d) Prove LBOC = 28 e) Consider ABOC and obtain an expression for cos (20) f) Obtain cos(20) = 2 cos² 0 - 1 g) Obtain an analogous formula for sin (20) 0 h) Put = in part f) to obtain the EXACT value of cos (22.5°)​