Up Your Score SAT, 2018-2019 Edition The Underground Guide to Outsmarting The Test

hyperbolas). Basically, a line is tangent to a circle if it makes a right angle with
the circle’s radius and intersects the circle at one point.

In  the circle  above,  only    the line    p   is  a   tangent line.

The one advantage   of  problems    that    give    you less    information is  that    you have    fewer   elements    to  consider.   The disadvantage    is  thatthey’re really  hard.

—Samantha

Example 1: A circle of the equation x^2 + y^2 = 25 has a tangent line at the
point (4,3). What is the equation of the tangent line?
First of all, we have to visualize this circle. Because there’s nothing after the
x’s and the y’s, the center of the circle is on the origin (0,0). The radius is the
square root of 25, and so it’s 5.