Which of the following statements is not true? a. parallel lines are lines in the same plane that never intersect. b. congruent figures have the same shape and same size angles and sides. c. similar figures must have the same shape and the same size. d. a rotation is when you turn a figure around a certain point.

C.Similar figures must have the same shape and the same size.

Step-by-step explanation:

Two figures are called similar if they have the same shape that is the ratio of their corresponding edges are in same proportion,

But it is not essential that they must have the same size.

For example, If we have two right triangles,

First having sides 3, 4, 5 and second having sides 9, 12, 15,

Since they are similar because their sides are in the same proportion,

Also, in the case of triangles size is called area of the triangle,

The area of  first triangle is 6 square unit, while second triangle has the area 54 square unit,

6 ≠ 54,

Thus, both triangle have the different sizes.

⇒ Third Option is incorrect.

Note:

Parallel lines have the same slope this is why they never intersect each other ⇒ First Option is correct.

Two figures are called congruent when they have same size and same shapes ⇒ Second Option is correct.

In rotation a figure is rotated around a point ⇒ Fourth option is correct.

y/x=18

step-by-step explanation:

(3x-8) or (3x+8)

step-by-step explanation: