12. Construct a right angle

Step 1: Draw a line segment \(PA\).

 

Step 2: Place the protractor on the line segment \(PA\) and the mid point of the protractor at point \(P\), as shown in the figure.

 

 

Step 3: On \(PA\) from the right side of the protractor start counting from \(0°\) in the ascending order (counter-clockwise direction) and finally mark a point \(Q\) using a sharp pencil at the point \(90°\) on the semicircular edge of the protractor.

 

 

Step 4: Remove the protractor and join \(PQ\).

 

We get the required angle \(∠APQ\) \(=\) \(90°\).