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MATHEMATICS FOR AIR CREW TRAINEES               19-21

(38) The chord of an airplane wing is 72 inches. If the center of pressure is at a point 28 percent of the distance along the chord from the leading edge, how many inches is it from the leading edge? 
20.16 inches. Answer

(39) The L/D ratio for an airfoil section is Lc/Dc. Find the L/D ratio when Lc = 0.0018 and Dc = 0.00008.

(40) Find the ratio of the areas of two circles having radii of 3 inches and 4 inches. (The areas are to each other as the squares of their radii.)               9/16 Answer.

SECTION III

ALGEBRA

                                             Paragraph
Purpose and scope ------------------------------ 20
Algebraic symbols ------------------------------ 21
Addition and subtraction of polynomials -------- 22
Multiplication and division of polynomials ----- 23
Evaluation of algebraic expressions------------- 24
Equations--------------------------------------- 25
Word problems ---------------------------------- 26 
Miscellaneous exercises------------------------- 27

20. Purpose and scope.-Algebra is the basis for all work in formulas and trigonometry. In the solution of many problems of these types the first thing that is done is to write facts in the form of an equation. To be able to handle such work, equations must be understood and the necessary background of algebraic manipulation must be thoroughly mastered. The following paragraphs contain exercises with accompanying explanations designed to give the student a working knowledge of necessary fundamentals of algebra. 

21. Algebraic symbols.-a. In working with general formulas, it is convenient to let numbers be represented by letters. In the actual evaluation of the formulas, the specific values are substituted for the letters. 

Example: d = 1/2 g t^2    if g=32, t=5

Solution: then d=1/2 X 32 X 25 = 16 X 25 = 400        Answer.

The above formula is solved for d. If it became necessary to solve for some other letter in the formula, other operations would be required. To perform such operations, it is essential to learn some of the fundamental characteristics of algebra. 

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Transcription Notes:
Do we ignore subscripts like superscripts?