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Area & Volume Learning Outcomes Find the area of square, rectangles, triangles, parallelograms, rhombuses, kites, trapezia and shapes which are composites of these. Find the circumference and area of a circle, to include inverse calculations. Find the area and circumference of a sector and segment of a circle. Find the surface areas and volumes of prisms. Find the surface area and volume of the cylinder to include inverse calculations Find the surface area and volumes of the cone and sphere to include inverse calculations. Find the surface areas and volumes of compound shapes most of which are everyday objects. Distinguish between formulae for perimeter, area and volume by considering dimensions.
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Area & Volume Area of Shapes Triangles Area = ½ base × perp. height A = ½ b × h 5cm 6cm 60 ° 8cm 12cm A C B b a c A = ½ ab sin C Area = ½ product of 2 sides × sine of angle between them
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Area & Volume Area of Shapes Trapezium One pair of parallel sides Total area = bh + ½.ah - ½.bh = ½.bh + ½.ah = h / 2 (a+b) Area 1 → b × h h b a 2 1 a - b Area 2 → ½ (a – b) × h Area of a trapezium = ½ (a +b) × h = h / 2 (a+b)
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Area & Volume Area of Shapes Parallelogram Area = a × b = length × perp. height a b Kite Area = ½ ab = ½ × length × width b a
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Area & Volume Area of Shapes Find the area of the following shapes 3cm 5cm 10cm 7cm 1. 8cm 6cm 12cm 2.
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Area & Volume Area and Perimeter Circles O C B A E D AB – diameter of circle OC – radius of circle DE – chord of circle Area of a circle A = π r 2 Perimeter of a circle Circumference C = π d C = 2 π r
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Area & Volume Area and Perimeter Find the area and perimeter of 12cm 8cm
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Area & Volume Area and Perimeter 1. The area of a circle is 51.6cm 2. Calculate its radius. 2. The circumference of a circle is 50cm. Calculate its area.
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Area & Volume Area and Perimeter 3. The radius of a car wheel is 53cm. How many revolutions does the wheel make in travelling 50m? ?
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Area & Volume Area and Perimeter 4. Find the shaded area. 8cm 10cm
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Area & Volume Sectors of a Circle Area and Perimeter Consider a sector of a circle which subtends an angle of 60° at the centre. Find (i) The area of this sector (ii) The arc length AB (iii) The perimeter of the shape OAB 60° r =5cmO B A
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Area & Volume Sectors of a Circle Area and Perimeter In general θ°θ° r Area = θ × π r 2 360 Arc length = θ × 2 π r 360
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Area & Volume Sectors, Segments, Chords and Area O BA 7 150° OA = radius AB = chord The chord AB subtends an angle of 150° at the centre of the circle. The radius of the circle is 7cm.
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Area & Volume Trigonometry sin x = opposite. hypotenuse cos x = adjacent. hypotenuse tan x = opposite adjacent Remember SOH CAH TOA 8 x 30° 1. O A H 15 x 40° 2. A O H 3 x 40° 3. O A H
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Area & Volume Volume of Prism Volume of a prism = cross sectional area × length Cylinder V = π r 2 h rhV 3 3.2 4 5 128 125 Complete the table below (cylinders) a) b) c)
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l h a b Area & Volume Volume of Prism Volume of a prism = cross sectional area × length Trapezoidal V = ½ ( a + b ) h × l 10 4 5 8 Cross-sectional area = Volume V = Example
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Area & Volume Volume of Prism Cone PyramidSphere h b a r h l r a, b = dimensions of base h = perpendicular height r = radius h = perpendicular height l = slant length V = 4 / 3 π r 3 V = 1 / 3 π r 2 h V = 1 / 3 × base area × height r = radius Find the volume of (i) Pyramid (ii) Cone(iii) Sphere a = 3, b = 4, h = 2 r =2, h = 4.5 r = 1.5
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Area & Volume Volume of Prism Find r. r 6 V = 300cm 3 Find r. r V = 250cm 3 10 h V = 500cm 3 Find h. h 5 10 Find h. V = 210cm 3
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Area & Volume Surface Area of a Cone, Sphere & Cylinder r h l Cone SA = π rl h r l l 2 = r 2 + h 2 Remember… r h cylinder SA = 2 π rh + 2 π r 2 SA = Curved surface area + Top + Bottom h 2 π r Curved area = = 2 π rh r Sphere SA =4 π r 2
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Area & Volume Surface Area of a Cone, Sphere & Cylinder Calculate the Surface Area of 3 5 b) 6 l 6 a) c) 5.2 r = 1.8 5 d) e) 14.8 4
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Area & Volume SOH CAH TOA Use Trig to find angle marked x in the following triangles 5cm 3cm x 5cm x 3cm 5cm x 10.4 14.6 x
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Area & Volume Using Trig in Area Calculations O BA 10.4 14.6 10.4 Find (i)The angle AOB (ii)The area of sector AOB (iii) Area of triangle AOB (iv)The shaded area
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Area & Volume Dimensions Distinguishing between length, area & volume r h Formulae can be used to calculate length e.g. Volume V = π r 2 h L 2 × L 2 = L 3 (Volume) b a Perimeter P = 2a + 2b L + L = L (Length) b a Area A = a × b L × L = L 2 (Area)
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Area & Volume Dimensions Further Examples a)4 l + 4 b + 4 h b)(l + b) 2 h 2 c)(2π)rh d)π(rh 2 – 1 / 3 h 3 ) e) πr (r 2 + h 2 ) f) 1 / 3 b 2 h
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Area & Volume Additional Notes
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Area & Volume Find the area of square, rectangles, triangles, parallelograms, rhombuses, kites, trapezia and shapes which are composites of these. Find the circumference and area of a circle, to include inverse calculations. Find the area and circumference of a sector and segment of a circle. Find the surface areas and volumes of prisms. Learning Outcomes: At the end of the topic I will be able to Can Revise Do Further
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Find the surface area and volume of the cylinder to include inverse calculations Find the surface area and volumes of the cone and sphere to include inverse calculations. Find the surface areas and volumes of compound shapes most of which are everyday objects. Distinguish between formulae for perimeter, area and volume by considering dimensions.
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