area of triangle is 1/2 * base * height.
we can turn this into a right triangle to get the height by saying the base is 5 and the hypotenuse of right triangle is 4. now to get the height we can use sine.
sin(a) = opposite/hypotenuse
sin (79) = x/4
x = 3.92
area = 1/2 * 3.92 * 5
area = 9.8
