In the figure below, ABCD is a parallelogram. What is the value of y – z?
A. 50
B. 55
C. 60
D. 65
E. 70
The sum of the degree measures of two consecutive angles of a parallelogram is 180, so 180 = (3x – 5) + (2x – 15) = 5x – 20 ⇒ 5x = 200 ⇒ x =40. Since opposite angles of a parallelogram are equal, y = 3x – 5 = 115 and z = 2x – 15 = 65. Then y – z = 50. The answer is (50).
If the length of a rectangle is 4 times its width, and if its area is 144, what is its perimeter?
A. 6
B. 24
C. 30
D. 60
E. 96
If the measures of the angles of a triangle are in the ratio of 1:2:3, and if the perimeter of the triangle is 30 + 10 (3)½, what is the length of the smallest side?
A. 20
B. 18
C. 15
D. 12
E. 10
What is the area of Triangle ABC?
A. 350
B. 360
C. 370
D. 375
E. 390
The area of Triangle CDE = 0.5(8)(15) = 60. Since the ratio of similitude for the two triangles (as calculated in solution C15) is 2.5, the area of Triangle ABC is (2.5)2 times the area of CDE: (2.5)2 × 60 = 6.25 × 60 = 375. The answer is (375).
What is the perimeter of Triangle ABC?
A. 80
B. 85
C. 95
D. 100
E. 105
Solution By the Pythagorean theorem, 82 + 152 = (CE)2 (CE)2 = 64 + 225 = 289 CE = 17. Then the perimeter of CDE = 8 + 15 + 7 = 40. Triangles ABC and CDE are similar (each has a 900 angle, and the vertical angle at C are congruent). The ratio of similitude is = 2.5, so the perimeter of ABC is 2.5 × 40 = 100. The answer is (100).