Math Problem Statement

Let a be a constant. The circle x² + y² − (a+2)x − 5ay + 19 = 0 passes through P(−1, 6). Find the equation of the tangent to the circle at P. Additional related questions are provided involving tangents to different circles and equations of lines touching these circles.

Solution

Thank you for uploading the image! I see a mathematical exercise involving tangents to circles. Let’s go through each question step-by-step to solve them. I'll start with Question 1 and proceed sequentially. Let me know if you'd prefer otherwise or need help on a specific problem first.


Question 1

The circle equation is:
x2+y2(a+2)x5ay+19=0x^2 + y^2 - (a+2)x - 5ay + 19 = 0 It passes through P(1,6)P(-1, 6). Find the equation of the tangent to the circle at PP.

Steps to Solve:

  1. Verify if P(1,6)P(-1, 6) satisfies the circle equation to confirm PP is on the circle: Substitute x=1,y=6x = -1, y = 6 into the circle equation: (1)2+62(a+2)(1)5a(6)+19=0(-1)^2 + 6^2 - (a+2)(-1) - 5a(6) + 19 = 0 Simplify: 1+36+a+230a+19=05829a=0a=2.1 + 36 + a + 2 - 30a + 19 = 0 \quad \Rightarrow \quad 58 - 29a = 0 \quad \Rightarrow \quad a = 2.

  2. Rewrite the circle equation with a=2a = 2: Substituting a=2a = 2 gives: x2+y24x10y+19=0x^2 + y^2 - 4x - 10y + 19 = 0

  3. Find the gradient of the radius at P(1,6)P(-1, 6): The center of the circle is obtained from the equation x2+y24x10y+19=0x^2 + y^2 - 4x - 10y + 19 = 0. Rewriting in standard form: (x2)2+(y5)2=25(x - 2)^2 + (y - 5)^2 = 25 The center is (2,5)(2, 5). The gradient of the radius is: mradius=y2y1x2x1=562(1)=13.m_{\text{radius}} = \frac{y_2 - y_1}{x_2 - x_1} = \frac{5 - 6}{2 - (-1)} = -\frac{1}{3}.

  4. Find the gradient of the tangent: The tangent is perpendicular to the radius, so: mtangent=1mradius=3.m_{\text{tangent}} = -\frac{1}{m_{\text{radius}}} = 3.

  5. Equation of the tangent: Use the point-slope form of a line equation with m=3m = 3 and point (1,6)(-1, 6): y6=3(x+1)y=3x+9.y - 6 = 3(x + 1) \quad \Rightarrow \quad y = 3x + 9. Rearrange to standard form: 3xy+9=0.3x - y + 9 = 0.

The correct answer is D: 3xy+9=03x - y + 9 = 0.


Would you like me to proceed with Question 2, or clarify anything so far?

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Analytic Geometry
Circle Equations
Tangents to Circles

Formulas

Equation of a circle: (x − h)² + (y − k)² = r²
Gradient of a line: m = (y₂ − y₁) / (x₂ − x₁)
Point-slope form of a line: y − y₁ = m(x − x₁)

Theorems

Perpendicular Tangent Theorem

Suitable Grade Level

Grades 10-12