Download presentation

Presentation is loading. Please wait.

1
**Surface Areas of Prisms & Cylinders**

Section 11-2

2
**Objectives To find the surface area of a prism**

To find the surface area of a cylinder

3
All About Prisms Prism - a polyhedron w/ exactly 2 congruent, parallel faces, called bases. Lateral faces - the faces that are not bases in a polyhedron Named by the shape of its bases Altitude - perpendicular segment that joins the planes of the bases Height (h) - length of the altitude

5
**Vocab Ctd. Lateral area - the sum of the areas of the lateral faces**

Surface area - the sum of the lateral area and area of the two bases

6
**Use a net to find the surface area of the cube.**

Draw a net for the cube. Find the area of one face. 112 = 121 The area of each face is 121 in.2. Surface Area = sum of areas of lateral faces + area of bases = ( ) + ( ) = 6 • 121 = 726 Because there are six identical faces, the surface area is 726 in.2.

7
You try Use a net to find the S.A. of the triangular prism

8
Formulas

9
**Use the formula L.A. = ph to find the lateral area and the formula **

Find the surface area of a 10-cm high right prism with triangular bases having 18-cm edges. Round to the nearest whole number. Use the formula L.A. = ph to find the lateral area and the formula S.A. = L.A. + 2B to find the surface area of the prism. The area B of the base is ap, where a is the apothem and p is the perimeter. 1 2 The triangle has sides of length 18 cm, so p = 3 • 18 cm, or 54 cm. Draw the base. Use 30°-60°-90° triangles to find the apothem.

10
**9 = 3 a longer leg 3 shorter leg**

(continued) 9 = a longer leg shorter leg 9 3 3 9 a = = = Rationalize the denominator. B = ap = 54 = 1 2 The area of each base of the prism is cm2. S.A. = L.A B Use the formula for surface area. = ph + 2B = (54)(10) + 2( ) Substitute = Use a calculator. Rounded to the nearest whole number, the surface area is 821 cm2.

11
You try Use formulas to find L.A. & S.A. of the prism

13
**All About Cylinders Has 2 congruent parallel bases, which are circles.**

Altitude - perpendicular segment that joins the planes of the bases Height - length of the altitude L.A. - area of resulting rectangle that can be formed by unrolling the cylinder S.A. - sum of the lateral area & area of bases

16
**The radius of the base of a cylinder is 6 ft, and its height is 9 ft**

The radius of the base of a cylinder is 6 ft, and its height is 9 ft. Find its surface area in terms of . S.A. = L.A B Use the formula for surface area of a cylinder. = rh + 2( r 2) Substitute the formula for lateral area of a cylinder and area of a circle. = (6)(9) (62) Substitute 6 for r and 9 for h. = Simplify. = 180 The surface area of the cylinder is ft2.

17
You try Find the S.A. of a cylinder with a height of 10cm and radius of 10cm in terms of pi. 400cm2

18
**Use the formula for surface area of a cylinder.**

A company sells cornmeal and barley in cylindrical containers. The diameter of the base of the 6-in. high cornmeal container is 4 in. The diameter of the base of the 4-in. high barley container is 6 in. Which container has the greater surface area? Find the surface area of each container. Remember that r = . d 2 S.A. = L.A B Cornmeal Container Barley Container Use the formula for surface area of a cylinder. = rh r 2 Substitute the formulas for lateral area of a cylinder and area of a circle.

19
**surface area of a cylinder.**

(continued) Cornmeal Container Barley Container S.A. = L.A B Use the formula for surface area of a cylinder. S.A. = L.A B = rh r 2 Substitute the formulas for lateral area of a cylinder and area of a circle. = rh r 2 = (2)(6) (22 ) = (3)(4) (32 ) Substitute for r and h. = = Simplify. = 32 = 42 Because in.2 in.2, the barley container has the greater surface area.

Similar presentations

OK

Goal 1: To find the surface area of a prism Goal 2: To find the surface area of a cylinder.

Goal 1: To find the surface area of a prism Goal 2: To find the surface area of a cylinder.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on railway reservation system Ppt on word association test saturday Ppt on electricity generation from municipal solid waste Ppt on molecular biology of head neck cancer One act play ppt on website Ppt on different types of forests in world Ppt on chapter 3 atoms and molecules worksheets Ppt on energy conservation in india Download maths ppt on number system for class 9 Ppt on seasons in arabic