Refer to the figure, in which a unit circle is drawn. The line segment DB is tangent to the circle and is acute. (a)

Refer to the figure, in which a unit circle is drawn. The line segment DB is tangent to the circle and θ is acute.

(a) Express the area of AOBC in terms of sin (b) Express the area of AOBD in terms of sin (c) The area of the sector OBC of the circle is 10, where is measured in radians. Use the results of parts (a) and (b) and the fact that Area AOBC < Area OBC < Area AOBD to show that 1 < 0 sin 0 O 0 1 cose and cos 0. and cos 0. B X