. Practical mathematics : an elementary treatise covering the fundamental processes of arithmetic, algebra, and geometry, with a practical presentation of logarithms and curve plotting. 90° while one-half, two-thirds, andone-third of a right angle would rq>_resent angles of respectively 45°J60°, and 30°, as shown in Fig. Drawing Work, it will be foundthat the 45° triangle and the 30°— 60° triangle are useful articlesof equipment, but when it comesto accurate values of angles, somedevice like a protractor, Fig. 14,showing degrees and fractions of de-grees, is necessary. Each degree isd
. Practical mathematics : an elementary treatise covering the fundamental processes of arithmetic, algebra, and geometry, with a practical presentation of logarithms and curve plotting. 90° while one-half, two-thirds, andone-third of a right angle would rq>_resent angles of respectively 45°J60°, and 30°, as shown in Fig. Drawing Work, it will be foundthat the 45° triangle and the 30°— 60° triangle are useful articlesof equipment, but when it comesto accurate values of angles, somedevice like a protractor, Fig. 14,showing degrees and fractions of de-grees, is necessary. Each degree isdivided into 60 equal parts called minutes, , and each minute into60 equal parts called seconds, . Thus to represent an angle of 23degrees, 47 minutes, and 9 seconds, write 23° 47 9. The relations of these units may be summarized as follows: 60 seconds () = 1 minute () 60 minutes = 1 degree (°) 360 degrees = 1 circle Two angles are complementarywhen their sum is equal to one rightangle or 90°; they are supplementwrywhen their sum is equal to two rightangles or 180°. Thus, an angle of. Fig. 14. Protractor. 33° is the complement of one of 57° because 33 -fof 148° and 32° are supplementary because 148 PROBLEMS FOR PRACTICE 1. How many seconds in 180 degrees ? 57 = 90. Anglesf 32 = 180. Ans. 648,000Ans. 2} Ans. 78° 12 57Ans. 48° 55 33 2. How many right angles in 202° 30? 3. What is the complement of 37°? 4. What is the complement of 11° 47 3? 5. What is the supplement of 131° 4 27? 6. Does an acute angle contain more or less than 90°? Anobtuse angle? 7. In Fig. 12, the angle A 0 C is, say, 52°; find the value of thethree other angles about the point 0. 8. How many seconds in 30? 102 PRACTICAL MATHEMATICSPOLYGONS 77. A polygon is a plane figure bounded by straight boundary lines are called the sides and the sum of the sides iscalled the perimeter.
Size: 2200px × 1136px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectmathematics, bookyear
