8th MENSURATION

Information about 8th MENSURATION

Published on May 31, 2013

Author: allwynasir

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PowerPoint Presentation: By- S.JASMINE SUGIRTHA MENSURATION Surface areas and Volumes For Class : VIII KENDRIYA VIDYALAYA , VIJAYANARAYANAM S.JASMINE SUGIRTHA 1 MATHS Contents: Contents Introduction Trapezium Rhombus Cube Cuboid Cylinder Table Question Bank S.JASMINE SUGIRTHA 2 MATHS Introduction: Introduction Area of a trapezium =half of the sum of the length of parallel sides x perpendicular distance between them. a rhombus =half the product of its diagonals {d1 x d2} Surface area of a solid is the sum of the areas of its faces. S.JASMINE SUGIRTHA 3 MATHS Introduction continued…: Introduction continued… Surface area of a cuboid =2(lb +bh +hl) a cube =6l² a cylinder =2 π r (r+h) Volume –amount of region occupied by a solid is called its volume. S.JASMINE SUGIRTHA 4 MATHS Introduction continued…: Introduction continued… Volume of a cuboid=l x b x h a cube =l³ a cylinder= π r²h 1 cm³=1ml 1l=1000 cm² 1 m³=1000000 cm³=1000 l S.JASMINE SUGIRTHA 5 MATHS TRAPEZIUM: TRAPEZIUM A trapezium is a quadrilateral whose two sides are parallel. ABCD is a trapezium such that AB and CD are its two parallel sides while AD and BC are its non-parallel sides. Each of the two parallel sides of b trapezium is called base of the trapezium. The distance between the two bases (parallel sides) is called the height or altitude of the trapezium. Area of trapezium =half of the sum of the length of parallel sides x perpendicular distance between them. A D C B S.JASMINE SUGIRTHA 6 MATHS Cube: Cube A cube is b 3-D figure whose length , breadth and height are equal. It has six faces and all are squares and identical. Surface area of a cube = 6 x (length of the side)² Volume of a cube = (side)³ S.JASMINE SUGIRTHA 7 MATHS Rhombus: Rhombus It is a quadrilateral whose all sides are equal out of which 2 opposite sides are parallel and none of the angles are right angles. Area of rhombus=½ x d1 x d2,where d1 and d2 are 2 diagonals S.JASMINE SUGIRTHA 8 MATHS CUBOID: CUBOID A cuboid is b 3-D figure which has six rectangular faces and opposite faces are identical. There are three pairs of identical faces. Surface area= 2x(lb + bh +lh) Volume= l x b x h S.JASMINE SUGIRTHA 9 MATHS Cylinder : Cylinder Cylinder is a 3–D figure which has one curved surface and two circular faces which are identical. Surface area of cylinder= 2 π r (r + h) Volume of cylinder= π r²h S.JASMINE SUGIRTHA 10 MATHS Table: Table Figure Volume Surface area Cuboid L x b x h 2(lb +bh +hl) Cube 6( l ) ² l ³ Cylinder π r²h 2 π r (r + h) S.JASMINE SUGIRTHA 11 MATHS Question Bank Multiple-choice Questions: Question Bank Multiple-choice Questions (i) Area of triangle (a) b x b (c) b x b (b) ½ x b x h (d) b x a Ans- ½ x b x h (ii) If the number of cement bags used to construct a path is needed, then the formulae to find the number of cement bags is - (a) area of path + area cemented by 1 bag S.JASMINE SUGIRTHA 12 MATHS PowerPoint Presentation: (b) Area of the path x area of place cemented by 1 bag (c) Area of the path / area of the cemented place by 1 bag (d) none of these Ans- Area of the path / area of the cemented place by 1 bag (iii) What is the area of circle? (a) b x h (c) π r² S.JASMINE SUGIRTHA 13 MATHS PowerPoint Presentation: (b) l x b (d) all of these Ans- π r² (iv) Area of the rhombus- (a) [area of triangle-1 + triangle-2] (b) length x breadth (c)½h(a+b) (d) diagonal 1 x diagonal 2 Ans- diagonal 1 x diagonal 2 (v) Volume of a cylinder is (a) l x b x h (b)l ³ (c) π r²h (d) None of these Ans- π r²h S.JASMINE SUGIRTHA 14 MATHS PowerPoint Presentation: (vi) How many centimeters make a litre? (a)100 cm (b)1000 cm³ (c)both (b) and (a) (d) All of the above Ans- b)1000 cm³ (vii)How many pairs of faces in cuboids are identical? (a) 3 pairs (b) 6 pairs (c) 5 pairs (d) 10 pairs Ans- 3 pairs (vii) Perimeter of parallelogram (a) l x b (b) 2(l + b) (c) 4 x sides (d) None of these Ans- None of these S.JASMINE SUGIRTHA 15 MATHS PowerPoint Presentation: (ix) Perimeter of circle (a) 2(l+b) (b) 3s (c) 2 π r (d) 4s Ans- 2 π r (x) Which are identical parts in cylinder (a) One curved surface and three circular faces (b) Two curved surface and one circular face (c) Both (a) and (b) (d) None of these Ans- None of these Correct answer-One curved surface and two circular faces S.JASMINE SUGIRTHA 16 MATHS Short answer type questions: Short answer type questions (1) What is triangulation? Ans- Splitting a quadrilateral into triangles, finding their areas and hence that of parallelogram (2) Find the area of a rhombus whose diagonals are of lengths 10 cm and 8.2cm . Ans- Area of rhombus= d1x d2 where d1,d2 are lengths of diagonals . =10 x 8.2 cm ² =41 cm² (3) Find the volume of the cube which has dimensions 2 x 2 x2 cm Ans- Volume of the cube = 6(l)² = 6(2)²=6 x 4 = 24 cm³ (4) In which unit is the volume expressed? Ans- cubic centimeter (cm³) S.JASMINE SUGIRTHA 17 MATHS PowerPoint Presentation: (5)Find the area of quadrilateral PQRS shown in the figure. Ans- d=5.5 cm,h1=2.5 cm,h2=1.5 cm Area= ½ d(h1 + h2) =½ x 5.5 x (2.5+1.5)cm² =½ x 5.5 x 4 cm² =11 cm² P S R Q 1.5 5.5 2.5 S.JASMINE SUGIRTHA 18 MATHS PowerPoint Presentation: Presentation made by – For Class : VIII KENDRIYA VIDYALAYA ..VIJAYANARAYANAM S.JASMINE SUGIRTHA S.JASMINE SUGIRTHA 19 MATHS : thank you S.JASMINE SUGIRTHA 20 MATHS

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