Introduction All the shapes we see around us are formed using curves or lines. We can see corners, edges, planes, open curves and closed curves in our surroundings. We organise them into line segme
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Right And Straight Angles You have heard of directions in Geography. We know that China is to the north of India, Sri Lanka is to the south. We also know that Sun rises in the east and sets in the
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Acute Obtuse and Reflex Angles We saw what we mean by a right angle and a straight angle. However, not all the angles we come across are one of these two kinds. The angle made by a ladder
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Measuring Angles The improvised ‘Right-angle tester’ we made is helpful to compare angles with a right angle. We were able to classify the angles as acute, obtuse or reflex. But this d
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Perpendicular Lines When two lines intersect and the angle between them is a right angle, then the lines are said to be perpendicular. If a line AB is perpendicular to CD, we write AB⊥ CD &nb
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Classification of Triangles Do you remember a polygon with the least number of sides? That is a triangle. Let us see the different types of triangle we can get. Take some more triangles an
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Quadrilaterals A quadrilateral, if you remember, is a polygon which has four sides. (a) Both of you will have a pair of 30°– 60°– 90° set-squares. Place them as sho
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Polygons So far you studied polygons of 3 or 4 sides (known as triangles and quardrilaterals respectively). We now try to extend the idea of polygon to figures with more number of sides. We may cl
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