Question

Which instrument(s) do we use to draw a circle?
A) Scale and Set Square
B) Scale and Protractor
C) Scale and Compass
D) Scale

Answer 1

Hint: We will first get to know about every tool and its uses. After that we will think about drawing a circle from it. If we see that it is possible, we will just go ahead with that option.

Complete step-by-step answer:
We will evaluate each option one by one and then see if we can use it.
has scale and set square
Scale can be used to measure the radius after the circle is being drawn but to draw a circle, we need something else. So, D) is discarded
Setsquare: A set square or triangle (American English) is an object used in engineering and technical drawing, with the aim of providing a straightedge at a right angle or other particular planar angle to a baseline. Here is a picture for your reference:-

We definitely cannot draw a circle with it.
Hence, A) is discarded.
Now, let us talk about protractor in B):
A protractor is a measuring instrument, typically made of transparent plastic or metal, for measuring angles. Here is a picture for your reference:-

We cannot draw a circle with it as well as it is made for measuring angles.
Hence, B) is discarded.
So, we are only left with option C.
In order to draw a circle, first we need a compass and we need to take the required radius length with the help of a scale. Here, is a picture of compass for the reference:-

We can use this by putting the sharp point on a paper and then rotating it to get a neat circular shape because the distance of the pencil from the sharp point remains the same.
Now, we will definitely require a ruler as shown below to measure the radius by putting the zero of the ruler on the center where we placed the sharp end of the compass and then measuring the length upto the circle boundary.

So, the required tools are scale and compass.

Hence, the correct option is (C).

Note: Most of the students will think that they don’t need a scale but we definitely need a scale to measure the radius of the circle.
Students may also get confused by the shape of the protractor that they can use to draw a semi-circle and then invert it to draw the left out part of the circle. But that is not necessary because if our protractor is somehow exactly semi-circle in shape, we may mess it up while inverting and drawing.