Transcribed Image Text: ** Example 15: An Application. The miter angle is the angle at which a saw or miter
box must be set to cut a piece of stock to form a joint. It is equal to half the angle
between the pieces to be joined. Find the miter angle for the pentagonal window in
Fig. 6-59.
Solution: The sum of the angles of the pentagon are, with n = 5.
sam of angles = (-2)180°
=(5-2)180-540
Each interior angle is then 540/5= 108. The miter angle is half of that, on
0=54°
Exercise 3 Quadrilaterals
1. Find the area and perimeter of
(a) a square of side 5.83 in.
(b) a square of side 4.82 m.
(c) a rectangle measuring 384 cm x 734 cm.
(d) a rectangle measuring 55.4 in. by 73.5 in.
190
2. Find the area of
(a) a parallelogram whose base is 4.52 ft and whose altitude is 2.95 ft.
(b) a parallelogram whose base is 16.3 m and whose altitude is 22.6 m
(c) a rhombus whose base is 14.2 cm and whose altitude is 11.6 cm
(d) a rhombus whose base is 382 in, and whose altitude is 268 in.
(e) a trapezoid whose bases are 3.83 m and 2.44 m and whose altitude is 1.86 m.
(f) a trapezoid whose bases are 33.6 ft and 24.7 ft and whose altitude is 15.3 ft.
Applications
3. What will be the cost, to the nearest dollar, of flagging a sidewalk 312 ft long
and 6.5 ft wide, at $13.50 per square yard?
4. How many 9-in-square tiles will cover a floor 48 ft by 12 ft?
5. What will it cost to carpet a floor, 6.25 m by 7.18 m, at $7.75 per square meter?
6. How many rolls of paper, each 8.00 yd long and 18.0 in. wide, will paper the
sides of a room 16.0 ft by 14.0 ft and 10.0 ft high, deducting 124 ft² for doors
and windows?
3608
FIGURE 6-61
20.0
Chapter 6 Geometry
7. What is the cost of plastering the walls and ceiling of a room 40 ft long. 36 ft
wide, and 22 ft high, at $8.50 per square yard, allowing 1375 ft² for doors,
windows, and baseboard?
8. What will it cost to cement the floor of a cellar 25.3 ft long and 18.4 ft wide,
at $3.50 per square foot?
720
9. Find the cost of lining a topless rectangular tank 68 in. long, 54 in. wide, and 48 in
deep with zinc, weighing 5.2 lb per square foot, at $1.55 per pound installed.
10. A parcel of land lies between two parallel streets, Fig. 6-60. How many acres will
remain in the parcel after the strip shown is taken for a new street? (1 acre-
43,560 ft²)
0
New Street
FIGURE 6-58
75.0
FIGURE 6-59
845
Street
/Street (
350 f
FIGURE 6-60
11. Brick Requirement. Estimate the number of bricks needed for a wall 13 x 18 f.
having one door 4 ft Xx 9 ft and two windows each 3 ft x 6 ft. Each brick has faces
measuring 8 x 2¹/4 inches, with half-inch joints between bricks.
12. Squares of Roofing Material. Roofing material is often specified in squares,
where one square equals 100 ft². How many squares of shingles are needed to
cover the roof of Fig. 6-61, neglecting waste?
13. Miter Angles: Calculate the miter angle for a
(a) triangular window (equilateral)
(b) square or rectangular frame
(c) hexagonal window
(d) octagonal wall clock
6-4 The Circle
A circle, Fig. 6-62, is a plane curve in which all points are at a given distance
(called the radius) from a fixed point (called the center). The diameter is twice the
radius. The diameter cuts the circle into two semicircles.
Circumference and Pi (#)
The circumference of a circle is its total length, or the distance around.
■ Exploration:
Try this. Wrap a strip of paper around a circular object, such as a jar lid, and mark
the point where it starts to overlap. The length from the mark to the end of the strip