Answer:
[tex]\displaystyle EF \approx 15.9[/tex]
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Equality Properties
- Multiplication Property of Equality
- Division Property of Equality
- Addition Property of Equality
- Subtraction Property of Equality
Trigonometry
- [Right Triangles Only] SOHCAHTOA
- [Right Triangles Only] cosθ = adjacent over hypotenuse
Step-by-step explanation:
Step 1: Define
Angle θ = 28°
Adjacent Leg = EF = x
Hypotenuse = DF = 18
Step 2: Solve for x
- Substitute in variables [Cosine]: [tex]\displaystyle cos28^\circ = \frac{x}{18}[/tex]
- [Multiplication Property of Equality] Multiply 18 on both sides: [tex]\displaystyle 18cos28^\circ = x[/tex]
- Evaluate trig: [tex]\displaystyle 18(0.882948) = x[/tex]
- Multiply: [tex]\displaystyle 15.8931 = x[/tex]
- Rewrite: [tex]\displaystyle EF = 15.8931[/tex]
- Round: [tex]\displaystyle EF \approx 15.9[/tex]