Question the-le

4.1 Lines, Angles, and Triangles - Triangle inequality
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  • The lengths of the sides are x, y, and z.
  • A note indies the figure is not drawn to scale.

 

The triangle shown has a perimeter of 22 units. If x=9 units and y=7 units, what is the value of z , in units?

A.

6

B.

7

C.

9

D.

16

The lengths of the sides are x, y, and z. A note indies the figure is

Medium-difficulty · SAT Math · Lines, Angles, and Triangles — Triangle inequality. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice A is correct. The perimeter of a triangle is the sum of the lengths of its three sides. The triangle shown has side lengths x , y , and z . It's given that the triangle has a perimeter of 22 units. Therefore, x + y + z = 22 . If x = 9 units and y = 7 units, the value of z , in units, can be found by substituting 9 for x and 7 for y in the equation x + y + z = 22 , which yields 9+7+z=22, or 16+z=22. Subtracting 16 from both sides of this equation yields z = 6 . Therefore, if x = 9 units and y = 7 units, the value of z , in units, is 6 .

Choice B is incorrect. This is the value of y , in units, not the value of z , in units.

Choice C is incorrect. This is the value of x , in units, not the value of z , in units.

Choice D is incorrect. This is the value of x + y , in units, not the value of z , in units.