 Hello and welcome to this session. In this session we will identify two dimensional figures obtained from the cross-section of three dimensional objects. We will also identify three dimensional figures obtained by rotating two dimensional figures. Now let us see how to identify two dimensional figures from cross-section of three dimensional objects. Now three dimensional figure or we can say 3D figure is a solid which has length, width and depth like cylinder, cone, sphere and two dimensional figure or we can say 2D figure only length and width like rectangle, circle, square, triangle etc. Now when we are playing intercept or slices a solid figure we obtain very interesting shapes. First of all let us understand the meaning of cross-section. Now when a plane intersects or cuts a solid then the intersection of the plane and solid is called cross-section. Now let us take one illustration in which we will slice the solid with a plane in three different ways and we will identify the two dimensional figures that is obtained. Here we have taken a cylinder. In first figure we have sliced the cylinder vertically with a plane and here the plane divides the cylinder in two halves. Now we see the shape of the cross-section formed after cutting the cylinder with this plane vertically and it is of a rectangle that is the shape of cross-section is of a rectangle which is a two dimensional figure. In the second figure we have sliced the cylinder at an angle that is we have sliced the cylinder by a plane at an angle. Here we get oval shape of the cross-section. Now in the third figure we have sliced the cylinder horizontally by the plane and we see that here we are getting circular cross-section of this cross-section which is circular in shape. Now let us take one more example. Now when a sphere is cut horizontally we can see that shape of the cross-section is a circle. Also we see when a plane is sliced vertically then we see that shape of cross-section is triangle. Now let us discuss how to identify three dimensional figures obtained by rotating two dimensional figures. To understand this we will see an illustration in which we will rotate a right angle triangle ABC to obtain the solid cone. Now let us rotate the triangle about the line AB. Now rotating the triangle about the line AB we get shape of a cone. Now the direction of rotation does not matter we can rotate clockwise or anti-clockwise about the vertical line AB thus rotating a two dimensional figure that is right under triangle we get a three dimensional figure that is a cone. Now let us take one more example. What will be the solid formed when a rectangle is rotated about one of its edges. Here let us take the rectangle ABCG. Now we rotate it about edge AB in any direction. Now here we can see when we rotate this rectangle about edge AB in any direction we obtain a solid that is cylinder similarly when we rotate a circle about its diameter we obtain a sphere also we must note that the line around which we rotate the figure is called axis of rotation. So in this session we have learnt how to identify two dimensional figures obtained from the cross-section of three dimensional figures and this completes our session hope you all have enjoyed the session.