1. One way to determine the exact value of cos 51 cos 69 sin 51 sin 69 without using a calculator, is to use the identity cos (w + u) = cosw cos a sinwsinu in reverse. In other words, write the identity as coswcosu sinwsinu = cos (w +u) Now take to = 51, u = 69 and write cos 51 cos 69 sin 51 sin 69 = cos (51 + 69) = cos 120 If you go to the notes on trigonometric functions in Module One, you will nd a table that gives values of the trigonometric functions for angles including 120. That table gives cos 120 = ~,:;. Therefore cos 51 cos 69 sin 51sin 69 = %. Use an appropriate identity in reverse as above, to determine the exact value of sin 73 cos 28 cos 73 sin 28 without using a calculator. You must write down the steps to your answer. A correct answer that is not supported by any work will earn NO points 2. A triangle ABC has a = 10 cm, 6: 15 cm and c =13 cm. (a) Draw the triangle ABC and label its vertices and lengths of its sides in the standard way. (b) Solve the triangle ABC. Round off each angle to the nearest degree. You must show how you get your answers