When circle [tex]\( P \)[/tex] is plotted on a coordinate plane, the equation of the diameter that passes through point [tex]\( Q \)[/tex] on the circle is [tex]\( y = 4x + 2 \)[/tex]. Which statement describes the equation of a line that is tangent to circle [tex]\( P \)[/tex] at point [tex]\( Q \)[/tex]?

A. The slope of the tangent line is [tex]\( -\frac{1}{4} \)[/tex].
B. The slope of the tangent line is [tex]\( 4 \)[/tex].
C. The slope of the tangent line is [tex]\( \frac{1}{4} \)[/tex].
D. The slope of the tangent line is [tex]\( -4 \)[/tex].



Answer :

To find the equation of a line that is tangent to circle [tex]\( P \)[/tex] at point [tex]\( Q \)[/tex], we first need to understand the relationship between the diameter of the circle and the tangent line at that point.

1. Determine the Slope of the Diameter:
Given the equation of the diameter that passes through point [tex]\( Q \)[/tex]:
[tex]\[ y = 4x + 2 \][/tex]
This equation is in the slope-intercept form [tex]\( y = mx + b \)[/tex], where [tex]\( m \)[/tex] represents the slope. From the given equation, the slope [tex]\( m \)[/tex] (slope of the diameter) is:
[tex]\[ m = 4 \][/tex]

2. Find the Slope of the Tangent Line:
The slope of a line tangent to a circle at a given point is the negative reciprocal of the slope of the diameter at that same point. Hence, we take the negative reciprocal of 4:
[tex]\[ \text{slope of the tangent line} = -\frac{1}{4} \][/tex]

Given the choices, the statement that best describes the equation of a line that is tangent to circle [tex]\( P \)[/tex] at point [tex]\( Q \)[/tex] is:
[tex]\[ \boxed{\text{A. The slope of the tangent line is } -\frac{1}{4}.} \][/tex]