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Mensuration
Done by T.V.N.K. Sreevasthav
Introduction • Mensuration is the branch of geometry that deals with the measurement of area, length, or volume in 2D and 3D shapes. The 2D shapes can be drawn in a plane like square, rectangle, triangle, circle, etc. and 3D shapes cannot be represented in a plane like bricks, ice- cream cones, football, etc. Mensuration includes computation using mathematical formulas and algebraic equations. 2D-Shapes • RECTANGLE:- Area- lxb sq.units Perimeter – 2(l+b) units • TRIANGLE:- Area - x b x h sq.units
Perimeter – Sum Of All Sides. units
• SQUARE:- Area – a x a sq.units Perimeter – 4 x a units • CIRCLE:- Area - sq.units Some 3D shapes
Cube Cuboid Sphere Cylinder Cone
CUBE CUBE A cube is a 3-D solid Some Formulae shape, which has 6 faces. A cube is one of the • Surface Area of Cube = 6a2 square units simplest shapes in three- • Volume of cube = a3 cubic units dimensional space. All • Lateral Surface Area = 4a2 square units • Length of Diagonal of Face of the Cube = √2 a units the six faces of a cube • Length of Diagonal of Cube = √3 a units are squares CUBOID CUBOID • A cuboid is a three dimensional solid that has 6 Some Formulae faces (rectangular), 8 vertices and 12 edges. A cuboid has three dimensions such as length, width and height. A perfect cuboid is said to be a cuboid that has integer edges. • Lateral Surface Area (LSA) = 2h(l + b) sq. units • Consider Euler’s formula, then the relation • Total surface area TSA = 2( lb + bh + hl ) sq. units between Faces (F), Vertices (V) and Edges (E) of • Volume = lbh cubic units a cuboid satisfies the equation: • Perimeter = 4(l + b + h) units F+V=E+2 • Diagonal = √(l^2 + b^2 + h^2) units SPHER E SPHERE A sphere is three dimensional, geometrical shape, that has all its Some Formula surface points equidistant from a common point. The distance • Surface Area = Square units between the surface and the common • Volume = cubic units point is the radius and the common point is called center of sphere. HEMI - SPHERE Hemi-Sphere
The word hemisphere can be separated into Some Formulae
hemi, which denotes half, and sphere, which refers to the geometrical 3D shape in • Curved surface area of a hemisphere = 2 mathematics. Consequently, a hemisphere • Area of base = is a 3D geometric object that is made up of • Total Surface Area = 3 half of a sphere, with one side being flat • Volume of hemisphere = and the other being a bowl-like shape. CYLINDER CYLINDER A cylinder is a three-dimensional solid that Some Formulae holds two parallel bases joined by a curved surface, at a fixed distance. These bases are • Curved Surface Area = 2πrh square units • Total surface area = 2πr(r+h) square units normally circular in shape and the center of • Volume of the Cylinder = πr2h cubic units the two bases are joined by a line segment, which is called the axis. The perpendicular distance between the bases is the height, “h” and the distance from the axis to the outer surface is the radius “r” of the cylinder. CONE Cone A pyramid which has a circular Some Formulae
cross-section, unlike pyramid • Slant Height = √(r2+h2) units
which has a triangular cross- • Volume = ⅓ πr2h cubic units • Total Surface Area = πr(l + r) sq. units section. These cones are also stated as a circular cone. Some Questions on Mensuration 1. 1. A circle has a radius of 21 cm. Find its circumference and area. (Use π = 22/7). 2. If one side of a square is 4 cm, then what will be its area and perimeter? 3. If a cube has its side-length equal to 5cm, then its area is? For Answers
4. Find the height of a cylinder whose radius is 7 cm and the
total surface area is 968 cm2. 5. Find the height of a cuboid whose volume is 275 cm3 and base area is 25 cm2. 6. A rectangular piece of paper 11 cm × 4 cm is folded without overlapping to make a cylinder of height 4 cm. Find the volume of the cylinder. OR Go to the link below for answers