Question

Which of the following are models for perpendicular lines?
a) the adjacent edges of a postcard.
b) the lines of a railway track.
c) the line segment forming the letter ‘L’.
d) the adjacent edges of your math book.
e) the line segment forming the letter ‘V’.

Answer 1

Hint: To solve this question, we first need to understand what are perpendicular lines. So, two lines are said to be perpendicular if they intersect each other at an angle of \[{90^ \circ }\]. If the angle of intersection is other than \[{90^ \circ }\], then the lines are not perpendicular to each other.

Complete answer:
We will solve each example one by one and see whether they are perpendicular or not.
a) the postcard is of the shape of a rectangle i.e.; they are rectangular objects. Now we know that the adjacent sides of a rectangle intersect each other at right angles so, the adjacent edges of a postcard are perpendicular lines.
b) the lines of a railway track never meet each other i.e., they do not intersect each other so, they can’t be perpendicular lines because the first condition for being perpendicular is intersection.
c) the line segments forming the letter ‘L’ intersect each other and we can see that they intersect each other at \[{90^ \circ }\], so, they are perpendicular lines.
d) books are generally cuboidal in shape this means that each face is a rectangle. Now we know that the adjacent faces of the rectangle intersect at \[{90^ \circ }\] so, the adjacent edges of the math book will be perpendicular lines.
e) though the line segments forming the letter ‘v’ intersect each other but as we can see that the angle of intersection is not \[{90^ \circ }\], so, they are not perpendicular to each other.

Therefore, the correct option is A, C and D

Note: Parallel lines are the lines that never intersect each other and the distance between them always remains the same. In the above question, the lines of a railway track are the examples of parallel lines because they never meet each other and also the distance between them always remains fixed.