Grade 4 Geometry: Lines and Rays

Worked examples

Real problems from the practice worksheets, solved one step at a time.

1. Example 1

   Figure JK starts at point J and goes on forever through point K. Is it a point, a line, a line segment, or a ray?

   1. A point is one exact spot. A line goes on forever in both directions. A line segment has 2 endpoints. A ray has 1 endpoint and goes on forever in one direction.
   2. Count the endpoints: figure JK stops at J, but it never stops on the other side.
   3. So figure JK is a ray.

   Answer: ray

2. Example 2

   Lines PQ and GH are perpendicular. How many right angles do they make where they cross?

   1. Parallel lines never meet and stay the same distance apart. Perpendicular lines meet to form right angles (90°).
   2. Picture a plus sign (+). Count the square corners around the middle, where the two lines cross.
   3. So they make 4 right angles.

   Answer: 4

3. Example 3

   Lines RS and AB are perpendicular. How many degrees is each angle they make where they cross?

   1. Parallel lines never meet and stay the same distance apart. Perpendicular lines meet to form right angles (90°).
   2. Every angle formed by perpendicular lines is a right angle.
   3. A right angle measures 90 degrees.

   Answer: 90