Visualising Solid Shapes 15.3

Visualising Solid Shapes Full exercise on Visualising Solid Shapes, fully solved. This is a video tutorial for 7th class NCERT CBSE students. For other educational stuff, subscribe and press bell icon. Visualising Solid Objects Sometimes when you look at combined shapes, some of them may be hidden from your view. Here are some activities you could try in your free time to help you visualise some solid objects and how they look. Such visualisation is very helpful. Suppose you form a cuboid by joining such cubes. You will be able to guess what the length, breadth and height of the cuboid would be. If two cubes of dimensions 2 cm by 2 cm by 2 cm are placed side by side, what would the dimensions of the resulting cuboid be? As you can see when kept side by side, the length is the only measurement which increases, it becomes 2 + 2 = 4 cm. The breadth = 2 cm and the height = 2 cm. 1. Two dice are placed side by side as shown: Can you say what the total would be on the face opposite to (a) 5 + 6 (b) 4 + 3 (Remember that in a die sum of numbers on opposite faces is 7). 2. Three cubes each with 2 cm edge are placed side by side to form a cuboid. Try to make an oblique sketch and say what could be its length, breadth and height. VIEWING DIFFERENT SECTIONS OF A SOLID Now let us see how an object which is in 3-D can be viewed in different ways. One Way to View an Object is by Cutting or Slicing Slicing game: When you give a ‘vertical’ cut, you get several pieces. Each face of the piece is a square! We call this face a ‘cross-section’ of the whole bread. The cross section is nearly a square in this case. Beware! If your cut is not ‘vertical’ you may get a different cross section! Think about it. The boundary of the cross-section you obtain is a plane curve. Do you notice it? A kitchen play: Have you noticed cross-sections of some vegetables when they are cut for the purposes of cooking in the kitchen? Observe the various slices and get aware of the shapes that result as cross-sections. Play this Make clay (or plasticine) models of the following solids and make vertical or horizontal cuts. Draw rough sketches of the cross-sections you obtain. Name them wherever you can. EXERCISE 15.3 1. What cross-sections do you get when you give a (i) vertical cut (ii) horizontal cut to the following solids? (a) A brick (b) A round apple (c) A die (d) A circular pipe (e) An ice cream cone. #VisualisingSolidShapes #SolidShapes #NcertSolutions #solvedexercises #teaching #ncert #cbse #maths #MathematicsClassVII #schoolmadeeasy #samrules Make sure to Subscribe and get the latest tutorials for your delight :) http://www.youtube.com/subscription_center?add_user=sumitsumo Make sure to check out our other Video Tutorials! Also, check us out when we're posting other helpful videos all throughout the week to help you tell more and grow more using online video.