 Hello everyone, this is Shila Ratna Banswade from Walshan Institute of Technology, SolarPo. Today we are going to see the topic sections of solids and in that particularly we will be looking into the element cone. At the end of this session the students will be able to draw the sectional view of a cone. Now I suggest you at this point of the video kindly pause the video and think over the geometry of cone and its parameters. As we all know cone is a type of solid of revolution where when a right angle triangle is rotated through 360 degrees through one of its 90 degrees side we get the right angle cone. It does not have any faces rather it has a curved surface. There are no edges it has generators. The base is circular and it has an apex at the top. Let us move further. A cone base 50mm diameter and axis 50mm has its axis parallel to VP and inclined at 45 degrees to HV. The horizontal section plane cuts the cone through the midpoint of the axis and removes the portion containing apex of cone. Draw the elevation sectional plane. Now here in the question a cone has been given of 50mm diameter and axis 50mm. So diameter of the cone and height are 50mm. Let us proceed with the drawing. First the XY line. Now as the cone is inclined at 45 degrees to HP the initial condition will assume that the cone is resting on its base on HP. So depending upon the second condition we are going to finalize the first stage. So first stage will be the cone is placed on HP with its base in HP and its axis parallel to VP. So in this case let us proceed first by drawing the top view of the cone. The top view of the cone will be a circle of diameter 50mm. So this is the top view of the cone that is circle of the given diameter. Further let us divide this circle into equal number of parts. So either you can divide it in 8 parts or 12 parts as per your convenience. The more the number of parts the more smooth the curve will be in the further stages. So let us divide this circle into 8 parts and we will name the parts as 1 to 8. So this is the point of apex. Let us project all the points in the vertically upward direction. So point 1 will be projected vertically upwards, 2 and 8 being on the same line, 3 and 7 on the same line which is the axis also 4 and 6 on the same line whereas 5. Now the front view of the cone in the first stage will be a triangle as you can see on the screen of 50mm height. So a cone has 50mm diameter this and axis 50mm so height 50mm. Now let us join the generators. So you can see the generator joining with the apex and this is the axis of the cone. Now naming in the front view. So we have named as at the base 1 dash, 2 dash, 8 dash, 3 dash, 7 dash, 4 dash, 6 dash and 5 dash in the second condition. The second condition says that axis is inclined at 45 degrees to HP. So in the first condition the cone is resting on HP where axis is 90 degrees to HP. So we have to tilt this cone in such a way that this axis that is o3 dash 7 makes an angle of 45 degrees. So this is the second view. The second stage front view where axis makes an angle of 45 degrees with the xy line. So the same view we have drawn it in a tilted form where axis makes an angle of 45 degrees with xy or horizontal or horizontal plane. Naming. So this is the complete front view in the second stage further. Let us project the points from the front view that is second front view and first top view to get the second top view that is top view in the second stage. So projecting 1 dash from the front view and 1 from the previous top view we get this as 1. Next 2 dash, 8 dash projecting vertically downwards and 2 from top view is at this point. 8 from this point. Similarly we have projected all the points including the apex. So you can see 1 by 1 dash and 1, 2 and 8 by 2 dash 8 dash and 2 and 8 from this top view. Similarly 6 is obtained by projecting 6 dash from the front view and 6 from the top view. Similarly 4, 4 dash from the front view and 4 from the top view similarly 5 and the apex point. So these are the points that you get in the top view of the second stage. So let us join these points. So you can see this is the core where outer boundary should be dark and the inner part that is 6, 5 and 4 will be in dotted form as it will not be seen in the top view because the observer is at this position that is above the front view. So 4, 5 and 6 that is behind this part will not be seen directly. So we have drawn this as hidden part. You have joined the generator that is O8 and O2, O1, O3, O7, O6 and O4. So this is the front view and the top view in the second stage. Now let us move to the cutting plane. The horizontal section plane cuts the cone through the midpoint of the axis and removes the portion containing apex of the cone. So horizontal plane which is parallel to XY and it passes through the midpoint of the axis of the cone cuts the cone by removing the apex part. So as it is suggested that the plane is horizontal let us draw it in the front view. So this is the horizontal plane parallel to XY and passing through the midpoint of the axis. And this portion above the cutting plane is removed and the direction of observation will be this. So you will get the sectional top view. Now the cutting plane wherever cuts the generators of the cone let us consider those points. First point we obtain it as here, second over here, third at this point O3 dash 7 dash, fourth at O4 dash 6 dash and fifth at O5 dash. Let us name these points. So P1, P28, P37, P46 and P5. So let us project these points in the top view and name the points. So these are the points that you obtain by projecting P1 on O1 generator, P2, P8 on O8 and O2 respectively. Similarly P37 on generator O3 and O7 respectively, similarly P46 and P5. By joining these points you will get the required section view. So this is the required section of the solid when it is cut by a horizontal plane. Now in this case as the cutting plane is parallel to XY there is no need to draw a separate true shape of the section as this section view itself gives you the true shape as the cutting plane being parallel to XY. Darkening of the edges. Now this portion has been removed so this has to be darkened and in top view this part has to be darkened. The remaining part will darken. Thank you.