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Section 9.3. Area, Volume, and Surface Area. Area of a Rectangle. Area is measured in square units. A square unit is a square one unit on each side. For example, start with a rectangle with length ( l ) 3 units and width ( w ) 2 units. A = l • w A = 3 • 2 units 2 A = 6 units 2. 2.
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Section 9.3 Area, Volume, and Surface Area
Area of a Rectangle Areais measured in square units. A square unit is a square one unit on each side. For example, start with a rectangle with length (l) 3 units and width (w) 2 units. A=l•w A= 3•2 units2 A= 6 units2 2 3
2 2 Rectangle 2 3 2 3 3•2=6 A=lw 3 3 (3•2) = 3 1 A=bh 2 Area Formulas Parallelogram Triangle The diagonal of a parallelogram forms 2 congruent triangles. 3•2 = 6 A=bh Martin-Gay, Prealgebra, 5ed
B Square h b B b side side h More Area Formulas Trapezoid + area=side •side A=s•s=s2 Martin-Gay, Prealgebra, 5ed
Helpful Hint Area is always measured in square units. When finding the area of figures, check to make sure that all measurements are the same units before calculations are made. Martin-Gay, Prealgebra, 5ed
r Given a circle of radius, r,the circumference isC= 2r. Martin-Gay, Prealgebra, 5ed
Dividing the circle into 4 equal sectors, half the circumference, r, is blue and the other half is red. 8 equal sectors r r r r r r 16 equal sectors 32 equal sectors r r r r r r Area of a Circle Martin-Gay, Prealgebra, 5ed
64 equal sectors 128 equal sectors r r r r r r n 2 equal sectors r r r Area of a Circle Notice the rectangular shape. A = lw A = (r)r A =r2 Martin-Gay, Prealgebra, 5ed
Perimeter/ Circumference Plane Figure Drawing Area P=a+ b+c Triangle P=a+b+c+d Parallelogram A=bh P = 2l+ 2w Rectangle A=lw Square P= 4s A=s2 P=a+b+c+d Trapezoid C=d or 2r A=r2 Circle Martin-Gay, Prealgebra, 5ed
Volumemeasures the number of cubic units that fill the space of a solid. The volume of a box or can is the amount of space inside. Volume Volume can be used to describe the amount of juice in a pitcher or the amount of concrete needed to pour a foundation for a house. Martin-Gay, Prealgebra, 5ed
A polyhedron is a solid formed by the intersection of a finite number of planes. Surface Area The surface area of a polyhedron is the sum of the areas of the faces of the polyhedron. Surface area is measured in square units. Martin-Gay, Prealgebra, 5ed
The volume of a solid is the number of cubic units in the solid. 1 inch 1 centimeter 1 centimeter 1 inch 1 centimeter 1 inch 1 cubic centimeter 1 cubic inch Martin-Gay, Prealgebra, 5ed
Rectangular Solid height width length Volume =lengthwidth height V=lwh SA = 2lh + 2wh + 2lw Martin-Gay, Prealgebra, 5ed
Cube side side side Volume =sidesideside V= s3 SA= 6s3 Martin-Gay, Prealgebra, 5ed
Sphere radius Volume = Martin-Gay, Prealgebra, 5ed
Circular Cylinder height radius Volume= V=r2h SA= 2rh + 2r2 Martin-Gay, Prealgebra, 5ed
Cone height radius Volume =
1 2 side height ( ) · · 3 1 V= s2h 3 Square-Based Pyramid height side Volume = B = area of base, p = perimeter, l = slant height
Helpful Hint Volume is always measured in cubic units. Surface area is always measured in square units. Martin-Gay, Prealgebra, 5ed