Question

how to calculate the radius of the circle when its diameter is 42 cm. please explain since i am a bigger Calculate the radius of the circle when its diameter is 42 cm.

Answer 1

Answer:

The area of the circle whose diameter is 42 cm is 1,386 cm².

Step-by-step explanation:

To find the area of a circle, we would use the equation \pi r^2.

In this case we have the diameter, and that's 42 cm.

The radius of a circle is half of the diameter, therefore the radius would be 21 cm.

Now we know the radius,we can plug that in to our equation.

Your equation should look like this:

\pi(21~\text{cm})^2

We know that pi is a constant, and the value of pi is \bold{\dfrac{22}{7}}.

Now, you can solve.

\dfrac{22}{7}\times(21~\text{cm})^2

=\dfrac{22}{7}\times441~\text{cm}^2

Simplify;

1386~\text{cm}^2

When you are done solving, you'll get 1386 cm²

1386 cm² will be your FINAL answer.