Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

In the figure shown if area of circle with center o is 100pi and CA has length of 6 what is length of AB ?enter image description here

I looked around on the web and cant seem to get an idea of what the angles AOC and OCA inside the triangle would be. Any suggestions on how I would go about determining them ?

share|improve this question

2 Answers 2

up vote 4 down vote accepted

Given that the area of the circle is $100\pi$, its radius $OC$ is $10$. Using Pythagoras Theorem one finds that $OA=8$. From there you may work out $AB$ and use the inverse trigonometric functions to find the angles.

share|improve this answer
Thanks for the tip!! that helped. I was aiming for the wrong approach thinking that there might be some rule which defines the angles formed in such a case. –  Rajeshwar Jun 9 '12 at 11:41

The angles are not needed. From the area, we find that the radius is $10$. Thus by the Pythagorean Theorem, $OA=\sqrt{10^2-6^2}=8$. But $OB$ is a radius, so $OB=10$, and therefore $AB=OB-OA=2$.

share|improve this answer
Thanks Andre.. appreciate the solution , @Jasper tip was more than enough.. Thanks again –  Rajeshwar Jun 9 '12 at 13:57

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.