Explain
Height = Sin(20) x 9 = 3.078
Area = Base x Height x 1/2
Area = 14 x 3.078 x 1/2
Area =21.5 cm^2
Answer of the above question is 21.5 cm^2. You just implement the forumla and get the answer.
You are better to use the area formula.
area = 1/2 *absinC
= 1/2 * (9*14*sin 20)
etc