Answer:
C. 
Step-by-step explanation:
We have been given a triangle. We are asked to find the measure of angle Z using Law of cosines.
Law of cosines: 
, where, a, b and c are sides opposite to angles A, B and C respectively.
Upon substituting our given values in law of cosines, we will get:
Now, we will use inverse cosine or arc-cos to solve for angle Z as:
Therefore, the measure of angle Z is approximately 51 degrees.
The dimensions of a room are determined by its length, width and height. In this problem we will assign a length of 12', a width of 13', and a height of 8' (as standard ceiling heights in most homes are 8' high). To calculate the amount of molding needed for strips at the top of the room and the bottom of the room we need to find the perimeter of the room. A length of 12' and a width of 13' make this room a rectangle. Determine the perimeter by adding 12' + 13' and multiplying the sum by 2 to get 50'. Multiply 50' x 2 to account for a decorative strip of molding at the floor and the ceiling and you get 100' total molding needed.
The perimeter is the sum of all the sides, so P = (5x -7) + (3x-4) + (2x -6). Then group like terms so you have p = 5x + 3x + 2x -7-4-6 and end up with P = 10x - 17
The answer to the problem is B.
