Question

A common tangent of the two circles is

• A. $x=4$
• B. $y=2$
• C. $x+\sqrt{3}y=4$
• D. $x+2\sqrt{2}y=6$

Answer 1

The correct option is B $y=2$

A tangent to a circle is a line that touches the circle at only one point on its circumference. When the same line touches two circles, it is called a common tangent. There are multiple cases for the position of circles which results in different types of common tangents. Here $x=0$ is needed for draw a common tangent lines.

Answer B: $y=2$