Question 49·Easy·Geometry and Trigonometry

For area of a circle, use $A = \pi r^2$. Make sure you are not using the formula for circumference.

Once you know the radius, plug it into $A = \pi r^2$. Be careful to square the radius before multiplying by $\pi$.

In the Desmos calculator, type pi*(14/2)^2 to represent $A = \pi r^2$ with radius $r = 14/2$.

Look at the exact (symbolic) output. You should see $\pi$ multiplied by a whole number; that product is the circle's area in square centimeters.

The problem gives the diameter of the circle as 14 centimeters.

The radius is half the diameter:

The formula for the area of a circle in terms of its radius $r$ is

Now we will substitute $r = 7$ into this formula.

Substitute $r = 7$ into $A = \pi r^2$ and simplify:

So, the area of the circle is $49\pi$ square centimeters, which corresponds to choice C.