Hi,

I'm having trouble with a question, where I need to find the missing co-ordinate.

The question (3:C) is,

I have tried to solve for $\displaystyle k$ by using Pythagoras, but I am still getting the wrong answer, when looking at the answer booklet, and I don't know how to get a second possible answer.

My working is as follows:

If,

$\displaystyle C = (2,-7)$

$\displaystyle E = (5, k)$

$\displaystyle Length = 5$

$\displaystyle (5-2)^2 + (k+7)^2 = 5^2$

$\displaystyle 3 + k + 7 = 5$

$\displaystyle k = -5$

According to the answer book, the answers are $\displaystyle -3$ or $\displaystyle -11$.

Again, like all the solution to my questions, I'm sure there's a simple solution to this problem, I'm just missing it.

If anyone can tell me where I'm going wrong with this, and how to find the second possible answer, that would be great.

Thanks in advance.