Question

Instruments to draw a pair of parallel lines are
A. Protractor and a scale
B. Compass and a scale
C. Set square and a scale
D. None of these

Answer 1

Hint: Here we find the correct option by checking each option. We find the possibility from the given options which will help us create a set of parallel lines. Use the definitions of the given instruments for help.
* A scale is a measuring device that helps us to measure lengths in different units like meters, centimeters etc.

* Protractor is a tool that is in a D-shape. It helps us to measure angles.

* Compass is an instrument to draw arcs and circles by fixing one end at a point and moving the other end as per requirement.

* Set square is a triangular object that is used in drawing lines, lines of symmetry, analyzing an object etc. There are two types of set squares:
Having internal angles as \[{30^ \circ },{60^ \circ },{90^ \circ }\]
Having internal angles as \[{45^ \circ },{45^ \circ },{90^ \circ }\]

Complete step-by-step answer:
A. Protractor and a scale:
We know a protractor is a D-shaped tool that helps us to measure the angle and scale is an instrument that helps us to measure the length between two points.
Since both the instruments are only used for measuring, we cannot draw a set of parallel lines from these instruments.
B. Compass and a scale:
We know that compass helps to draw arcs and scale helps to measure the distance between two points.
We draw a straight line AB. Take any point P on the line. Take any other point outside the line and join the two points

Now fix one end at point P and with suitable radius cut an arc that cuts the line AB at M and PQ at N.

Now fix the compass at point Q and with same radius draw an arc intersecting the line PQ at point O

Measure the distance between M and N using a compass. Then fix one end of the compass at point O and radius as the distance between M and N, draw an arc that intersects the previous arc at point R.

Now draw a line joining points R and Q

So, we have a line parallel to the given line AB.
C. Set square and a scale
We draw a straight line AB with the help of a scale and take a point P outside the line.
 

Now use a set square and place its one side on the line AB such that we have the right angle in the downward direction.

Now we place a scale along with the perpendicular side of the set square

Now we fix the scale and move the set square upwards such that the side of the set square meets the point P. We draw a line along the side of the set square such that the line covers the point P.

So we get a set of parallel lines using a set square and a scale.

So, there are two correct options B and C.

Note: Students might get confused while constructing parallel lines using compass as there are several arcs to be drawn. Always make small sized arcs because if you construct arcs of larger size then you will have to draw a larger set of lines. Also, when shifting a set square keep in mind there should be no distance between the scale and the set square.