 Hi and welcome to the session. Today we will learn about the constructions related to angles. First of all let us see the construction of an angle of given ratio. Suppose we want to construct the angle of 45 degrees. So we will construct this with the help of a ruler and a protractor. First of all draw a line segment AB of any length. So here we have line segment AB. Now take your protractor and place the center of the protractor at point A and the 0 inch along the line segment AB. That is put the center of the protractor over here at point A and the 0 inch along AB. Now start with 0 near B and mark a point 45 degrees. So here is the point C. Now join AC. Thus angle BAC is the required angle of 45 degrees. Next let us learn the construction of a copy of an angle of unknown ratio. Here in this construction we are given angle ABC of unknown ratio and we need to construct a copy of the given angle. Now copy of this given angle means an angle of same measure. So for this first of all draw a line L and mark a point P on it. Now place the compasses at point B and draw an arc the rays of angle ABC at points X and Y. Like this now use the same compasses settings to draw an arc with P as center cutting the line L at point Q. Now open your compasses equal to the length XY that is place the pointer of the compasses at point Y and the pencil at point X. So this will measure the length XY. Now without changing the settings of the compasses place the pointer of compasses at point Q and draw an arc to cut the previous arc at point. So we got the point R. Now join PR PQ is a copy of angle ABC that is angle R PQ has the same ratio angle ABC. Now lastly let us see the construction of bisector of an angle. For this construction we are given angle ABC and we need to construct the bisector of this angle. So for this use your compasses and with A as center and any radius draw an arc to cut the rays of angle ABC at points X and Y. Like this now open your compasses more than half the length XY then with X and Y as center draw two arcs in the interior of angle ABC to intersect each other at point P. So we got the point P. Now join BP thus line segment BP is the required bisector of angle ABC. So with this we finished this session. Hope you must have understood all the constructions. Goodbye and take care and have a nice day.