Here's the question you clicked on:
SantanaG
Which of the following equations is used to find the value of c? pic attahced
I don't think this is a complete question... if you don't have the values of a and b, then these all seem to be same question after all. All are equally solvable.
You don't have enough information.
Depending on values of a and b and whether you want a complex no. or not.. the answer varies
For now all of the choices are valid until we get more information
Thats all the information i was given. Its like saying which equation would we use to find the value of c if there were a and b .. idk im confused thats why I asked this question..
what subject are you learning right now?
If it's pre-calc it's probably just asking about the Pythagorean Theorem and how to find the hypotenuse of a right triangle.\[a^2+b^2=c^2\]That's just my guess anyway...
http://www.mathwarehouse.com/ellipse/focus-of-ellipse.php i found this but it says a^2-b^2= c^2 an thats not an option.. :( so i think @Shane_B is right