Answer:

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
 
Explanation:
Step 1: Define
Identify variables
Angle θ = 45°
Adjacent Leg = 25
Hypotenuse = x
Step 2: Solve for x
- Substitute in variables [cosine]: 

 - [Multiplication Property of Equality] Multiply 25 on both sides: 

 - Rewrite: 

 - Evaluate: 
