Surface Area and Volume of Prisms & Cylinders Objectives: 1) To find the surface area of a prism. 2) To find the surface area of a cylinder. I. Surface Area of a Prism Prism – Is a polyhedron with exactly 2 congruent, parallel faces, called bases. Name it by the shape of its bases. Bases are Rectangles: Lateral Faces – All faces that are not bases. (Sides) Right Prisms vs Oblique Prisms Right Prism – Lateral faces are rectangles. Oblique Prism – Lateral faces are parallelograms Total Surface Area = Lateral Area + 2 Base Area Lateral Area – • If the base is a regular polygon all 4 rectangles will be congruent •If the base is a non regular polygon you should look at individual rectangles and calculate their areas with A = l•w Total Surface Area = Lateral Area + 2 Base Area Base Area – • Rectangle: A = l•w • Triangle: A = ½bh Ex.1: Find the Surface Area of the rectangular Prism. Area of Bases: Lateral Area A = l•w Left and right rectangles are congruent = 4•3 = 12 cm2 5cm A = l•w= 3•5 = 15 cm2 Front and back rectangles are congruent 3cm A = l•w= 4•5 = 20 cm2 Total = 15+15+20+20 4cm SA = LA + BA = 70cm2 + 24cm2 = 94cm2 =70 cm2 Ex.2: Find the total surface area of the following triangular prism. 5cm LA = l•w (5 x 12) = 60cm2 5cm (5 x 12) = 60cm2 (6 x 12) = 72cm2 h 4 cm 6cm 192cm2 BA = ½bh = ½(6)(4) = 12cm2 x2 24cm2 SA = LA + BA = 192cm2 + 24cm2 = 216cm2 12cm II. Finding Surface Area of a Cylinder Cylinder r Has 2 congruent, parallel bases Base → Circle height C = 2πr A = πr2 r h r Net of a Cylinder: LA is just a Rectangle! LA = 2rh Area of a circle BA = r2 r Circumference of the circle SA = LA + 2BA Ex.3: SA of a right cylinder LA = 2rh 6ft 9ft = 2(6)(9) Area of Base = 108ft2 BA = r2 = 339.3ft2 = (6)2 = 36ft2 x2 SA = LA + BA = 72ft2 = 339.3ft2 + 226.2ft2 = 226.2 ft2 = 565.5ft2