In a rectangular axis system, what is the area

In a rectangular axis system, what is the area of a parallelogram with the coordinates: (5,7), (12,7), (2,3), (9,3) ?
(a) 21.
(b) 28.
(c) 35.
(d) 49.
(e) 52.

The best answer is B.
First, draw the axis system and mark the 4 points. Connect the points to get a parallelogram. The area is calculated by the multiplication of one on of the bases and the height. The height is (7 – 3 = 4), the length of the base is (9 – 2 = 7).
The area is 4 x 7 = 28.



If the radius of a cylinder is doubled and so is the height, what is the new volume of the cylinder divided by the old one?
(a) 8.
(b) 2.
(c) 6.
(d) 4.
(e) 10.

The best answer is A.
The volume of a cylinder is (pie x R2) x (height of cylinder).
The new volume is (4 x 2 = 8) bigger.