Question

question 4 of 10 what is the formula for the area of a circle? a. a = πr b. a = π²r c. a = πd² d. a = πr²

Explanation:

Step1: Recall circle - area formula

The area formula for a circle is $A=\pi r^{2}$, where $A$ is the area and $r$ is the radius of the circle.

Step2: Analyze options

Option A: $A = \pi r$ is incorrect. This is not the area formula.
Option B: $A=\pi^{2}r$ is incorrect. There is no such formula for the area of a circle.
Option C: $A=\pi d^{2}$ is incorrect. The correct formula with diameter $d$ is $A=\frac{\pi d^{2}}{4}$ (since $d = 2r$ and $A=\pi r^{2}=\pi(\frac{d}{2})^{2}=\frac{\pi d^{2}}{4}$).
Option D: $A=\pi r^{2}$ is the correct formula for the area of a circle.

Answer:

D. $A = \pi r^{2}$