What's the area of a circle with diameter 18 units? Question 8 options: A) 9π units2 B) 81π units2 C) π units2 D) 18π units2

B) 81π units²

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Geometry

Radius of a Circle Formula: r = d/2

r is radiusd is diameter

Area of a Circle Formula: A = πr²

Step-by-step explanation:

Step 1: Define

Diameter d = 18 units

Step 2: Manipulate Variables

Radius r = 18 units/2 = 9 units

Step 3: Find Area

Substitute in r [Area of a Circle Formula]:                                                       A = π(9 units)²[Area] Evaluate exponents:                                                                              A = π(81 units²)[Area] Multiply:                                                                                                  A = 81π units²