Start with the formula for finding the area of a circle.
A=πr2
First, substitute the given information in the equation. You have the area and you know that pi is 3.14.
153.86=(3.14)r2
Next, divide the area by pi. This will help to get one step closer to figuring out the radius.
3.14)153.86¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Remember, when you divide decimals, to move the decimal two places in the divisor and the dividend.
314)15386¯¯¯¯¯¯¯¯¯¯¯¯¯¯
314)15386¯¯¯¯¯¯¯¯¯¯¯¯¯¯ 49− 1256 –––––––– 2826 − 2826–––––––0
So far, the answer is 49, but that is not the radius because r2 is on the right side of the equal sign.
49=r2
Then, you need to figure out which number times itself is equal to 49. You can figure this out by finding the factors of 49.
7×7=49
Now, you know that the radius is 7 inches because 7×7=49.
The radius is 7 inches.
Finally, to figure out the diameter, which is twice the radius, multiply the radius by 2.
7×2=14
The diameter is 14 inches.
hope this helps.
