A large tree stump is located SE of a household, that is found at the origin of the diagram. A land surveyor measures the tree stump to be 7km East of the household and 12km straight south of the household.
a) Show your work to find the exact value of the cosine trigonometric ratio.
b) State the reference and principle angle (rounded to the nearest tenth) that create the line between the house and the tree stump.
