# Are you good at Math?

<p>Jan. '09 QAS. Section 3 - Math....question 18. (grid-in). Has a circle and the tangent line. Asks for slope. I got 3/4....why is the answer 4/3? </p>

<p>Thanks.</p>

<p>Could you make a picture in paint or something?</p>

<p>Well...not many of us would have QAS's at all so you really should try to get a picture up.</p>

<p>That being said, I just did it and got 4/3.
I looked at it this way. The tangent line is perpendicular to the line from A to the origin. So if we find the slope of the line from A to the origin, we can take the negative inverse to find the tangent line.</p>

<p>We know that point A is (-4,y). Since the equation of the circle is x^2+y^2=25, if we substitute for x we can find the y value, which comes out to be 3. With this we can find the slope of the line from A to the origin, which is -3/4. Therefore the tangent line would be the negative inverse, or 4/3.</p>

<p>If you don't understand it I can elaborate a bit more.</p>

<p>fak, wow. thanks, can't believe I didn't think of using the origin as a coordinate.</p>