geometry t

© 2009 -2011 tutorco.com 1 GRADE 8 TOPIC: GEOMETRY 8/3/5/T Specific Objectives: Student will be able to find area and volume of cylinder. What they already know: Student knows about area and volume of cube and cuboid. Key Concept: Area and Volume of Cylinder. Plan of action: • Definition and properties of cylinder. • Formulae to find area and volume of cylinder. Cylinder: A solid tube with two long edges and two equal-sized circular ends. Total Surface Area of cylinder: 2r(r + h) Lateral Surface Area: 2rh Volume of a Cylinder Just multiply the area of the circle by the height of the cylinder: • Area of the circle: × r2 • Height: h • Volume = Area × Height = × r2 × h © 2009 -2011 tutorco.com 2 Suggested Examples: Example 1: What is the Volume of a cylinder with radius of 5 cm and height of 3 cm? Solution: r = 5cm h = 3cm Volume: r2h 3.14 x 5 x 5 x 3 235.5 cm3 Example 2: Find the surface area of cylinder if radius is 6cm and height is 10 cm. Solution: r =6cm ; h = 10cm Surface area= 2r(r + h) 2 x 3.14 x 6(6 + 10) 602.88 cm2 Example 3: The lateral surface area of cylinder of height 14 cm is 88 cm2. Find the diameter of the base of cylinder. Solution: h = 14 cm Lateral Surface area: 88cm2 = 2 x rh 2rh = 88 2 x 3.14 x r x 14 = 88 r = 88/87.92 r =1.00 cm So, diameter =2r =2cm