Help working with two points of a circle

[deano2727]

Hi all,

I'm currently preparing to resit a Math exam from a few years back I failed at college in order to graduate. I am weak at Math and haven't done it in sometime. I am having difficulty with the below kind of questions:

The diameter of a circle starts at (-101, -159) and ends at (-158, 62). What is the circumference of that circle with your answer rounded up to a whole number.

The answer for the above is 717 ± 1%, according to my Virtual learning environment, but I have no idea why. I tried using the distance formula to get the diameter, then divided the answer by 2 to get the radius which I then put in to the formula for getting the circumference.

Another question:
The radius of a circle starts at (173, -102) and ends at (53, -4). What is the area of that circle with your answer rounded up to a whole number.

The answer for the above question is 75,411 ± 1%. Is this the same as above and then just use the area of a circle formula instead?

I'd greatly appreciate if someone could run through these questions and explain how to get a (correct) number to plug in to the formulas from the two points.

Cheers.

 

[lev888]

Your approach looks good, please post your work for review.

 

[d.mehdoi]

I tried to solve the first question with my great paint skills. I hope this helps.


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Edit: I add the second one too. I realized that I calculated diameter for no reason.

 

[d.mehdoi]

Note: 98 and 120 should be changed on the triangle for the second question. I am unable to edit my posts to change it. It does not effect the result but 120 should be 98 and 98 should be 120 there.

 

[pka]

The diameter of a circle starts at (-101, -159) and ends at (-158, 62). What is the circumference of that circle with your answer rounded up to a whole number.
The answer for the above is 717 ± 1%, according to my Virtual learning environment, but I have no idea why. I tried using the distance formula to get the diameter, then divided the answer by 2 to get the radius which I then put in to the formula for getting the circumference.

Another question:
The radius of a circle starts at (173, -102) and ends at (53, -4). What is the area of that circle with your answer rounded up to a whole number.

Circumference is \(\displaystyle \pi\cdot D\) SEE HERE Using WolframAlpha is great to check answers.
If you find the length off the diameter \(\displaystyle \sqrt{(-101+158)^2+(-159-62)^2}\) then multiply by \(\displaystyle \pi\).